Off the beaten tracks: exploring three aspects of web navigation.
ABSTRACT This paper presents results of a long-term client-side Web usage study, updating previous studies that range in age from five to ten years. We focus on three aspects of Web navigation: changes in the distribution of navigation actions, speed of navigation and within-page navigation. "Navigation actions" corresponding to users' individual page re- quests are discussed by type. We reconfirm links to be the most important navigation element, while backtracking has lost more than half of its previously reported share and form submission has become far more common. Changes of the Web and the browser interfaces are candidates for causing these changes. Analyzing the time users stayed on pages, we confirm Web navi- gation to be a rapidly interactive activity. A breakdown of page characteristics shows that users often do not take the time to read the available text or consider all links. The performance of the Web is analyzed and reassessed against the resulting require- ments. Finally, habits of within-page navigation are presented. Although most selected hyperlinks are located in the top left corner of the screen, in nearly a quarter of all cases people choose links that require scrolling. We analyzed the available browser real estate to gain insights for the design of non-scrolling Web pages.
Off the Beaten Tracks:
Exploring Three Aspects of Web Navigation
Harald Weinreich1, Hartmut Obendorf2, Eelco Herder3, Matthias Mayer2
1VSIS, Department of Informatics
University of Hamburg, Germany
2ASI, Department of Informatics
University of Hamburg, Germany
3Department of Computer Science
University of Twente, The Netherlands
This paper presents results of a long-term client-side Web usage
study, updating previous studies that range in age from five to ten
years. We focus on three aspects of Web navigation: changes in
the distribution of navigation actions, speed of navigation and
“Navigation actions” corresponding to users’ individual page re-
quests are discussed by type. We reconfirm links to be the most
important navigation element, while backtracking has lost more
than half of its previously reported share and form submission has
become far more common. Changes of the Web and the browser
interfaces are candidates for causing these changes.
Analyzing the time users stayed on pages, we confirm Web navi-
gation to be a rapidly interactive activity. A breakdown of page
characteristics shows that users often do not take the time to read
the available text or consider all links. The performance of the
Web is analyzed and reassessed against the resulting require-
Finally, habits of within-page navigation are presented. Although
most selected hyperlinks are located in the top left corner of the
screen, in nearly a quarter of all cases people choose links that
require scrolling. We analyzed the available browser real estate to
gain insights for the design of non-scrolling Web pages.
Categories and Subject Descriptors
H.5.4 Hypertext/Hypermedia: User issues.
Human Factors, Design.
Hypertext, navigation, user modeling, clickstream study, browser
The World Wide Web is a system where the only constant is
change. New technologies and services have emerged on the ser-
ver side, allowing people to use their Web browser for manifold
activities and tasks: content management systems allow the reuse
of layout information and the dynamic creation of documents; in-
formation can be updated as frequently as required for news pages
and online shops. Functionality that used to reside on desktops is
made accessible through Web interfaces, covering an application
range from email, chat, and bulletin boards to complex appli-
cations like travel agencies, libraries and shops. Many of these
changes could not be foreseen when the Web and its client soft-
ware were designed as a hypertext information system.
While the technology serving the Web behind the scenes has seen
dramatic changes, the user interface of current Web browsers and
their integrated navigation support tools closely resemble those of
browsers from the early days of the Web. Most of the changes are
of technical nature, such as the integration of plug-ins and
interaction, but not directly relating to browsing support. Al-
though change here was slow and subtle, some new interaction
methods have been introduced that might influence user habits,
such as tabbed browsing (Figure 3) and mouse gestures .
There is a similar imbalance in focus between server-side and
client-side analyses of Web browsing behavior. Whereas page
requests to Web servers and search engines are commonly logged
and used for subsequent analysis of usage patterns, access to
cross-site browsing patterns is barred as this data is only available
on the client. Studies collecting clickstream data on client-side are
surprisingly scarce: the last reported long-term studies of browser
usage are at least five years old. Consequently, many aspects of
how people use their Web browsers today are either unknown or
unproven. As changes of the Web and in browser features could
have a major influence on user requirements that might be visible
in their actions, we felt the necessity for an update study. The ex-
isting long-term studies are of excellent quality but also of im-
pressive age; newer quantitative studies relate to specific tasks,
were often performed under laboratory conditions or had fairly
small sample sizes and thus fail to give an account of everyday
Web use. The study presented here captures a detailed stream of
user actions and page requests over a long period directly in the
working environment, which enabled us to give a fairly consistent
account of periods of users’ browsing activity.
Based on this data some recommendations for Web design are
reconsidered. Navigation actions indicate that the Web has
evolved to a hybrid between information system and online appli-
cation. Users’ speed of navigation is high, even on pages that are
rich in content and links. This rapid activity is set in relation to
the measured responsiveness of the Web to identify limiting fac-
tors. The positions of selected links provide insights in user habits
and issues with current page design. We finally find that in con-
trast to common belief, Web browsing is an activity that needs to
share the users’ attention – and screen space – with other appli-
Copyright is held by the International World Wide Web Conference
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use, and personal use by others.
WWW 2006, May 23–26, 2006, Edinburgh, Scotland.
2. RELATED STUDIES
How users browse the Web has been subject to research almost
from the start. Many previous studies are based on data found in
server logs, analyzing various aspects of user navigation [18; 19;
35; 40]. However, server logs only report on user actions for a
single site, caching mechanisms hide some of the interesting re-
visits, and interaction with the browsing application remains con-
cealed. In contrast, several observational short-term studies
examined in detail on how people use the Web; screen captures,
video coverage, and Web diaries have been successfully applied
to extract contextual information of Web browsing activity [5; 17;
25; 38]. However, as these studies are very time-consuming, they
can cover only a very limited period of user activity and the size
of the user sample is usually small. Also, these studies can hardly
report on quantitative changes and may be biased by the test envi-
Since 1994, only three long-term studies have tried to analyze the
clickstream created by the interaction of user and Web browser.
Of these studies, only two recorded navigation actions – and both
are over 10 years old by now. In 1994, the first long-term client
usage study was described by Catledge and Pitkow . They used
an instrumented version of XMosaic on their departmental Sun
workstations to analyze the actions of users that lead to page re-
quests. Their study covered the Web browsing activity of 107
users for 21 days. Catledge and Pitkow identified different navi-
gation strategies and found that users operate only on small areas
within sites. The back button was found to be the second most im-
portant user interface element accounting for 41% of navigation
actions, second only to hyperlinks (52%). Other actions, such as
“archiving” actions that lead to saving or printing a page, were
In 1995, Tauscher and Greenberg focused on history support and
analyzed the revisitation behavior of their participants . They
defined the “recurrence rate” as the probability of the next visited
page having been visited before by the same user. A measured
rate of 58% led them to the conclusion that the Web is a ‘recur-
rent system’, although they also found that most revisits are short-
term: only 15% of page revisits are not in the list of the last 10
visited pages. Finally, in 1999, Cockburn and McKenzie retroacti-
vely analyzed the Netscape history and bookmark files of their
participants . Their users visited more pages per day, but at the
same time the revisitation rate increased to 81%. They also found
that Web use is rapidly interactive and users often visit many
pages within seconds successively. They gained new insights into
homepage and bookmark use. People tend to have many book-
marks, but use only few of them.
3. THE WEB BROWSING STUDY
25 unpaid volunteers participated in the Web logging study. Two
1.5 hour interviews at the beginning and end of the study were
used to gather demographical data and information on general
use, but also to confirm some interpretations of the captured data,
e.g. concerning the use of multiple windows. Six (24%) of our
participants were female. Ages ranged from 24 to 52 years (mean:
30.5). All our participants were experienced, browsing the Web
for 3 to 12 years (mean: 8). Most of them came from Germany
and the Netherlands (three Germans worked in Ireland and New
Zealand) and all interviews were conducted in their native lan-
guage. While all eight participants from the Netherlands (32%)
worked as university employees in computer science, nine partici-
pants (36%) had a different background: two worked in psy-
chology, and one each in sociology, geology, electrical enginee-
ring, trading, coaching, history, and photography. Seven addi-
tional participants began the study, but dropped out for personal
or technical reasons and had to be excluded from the analysis.
The length of the study varied individually from 52 to 195 days
(mean: 105 days). We were able to confirm (see Section 3.3)
137,272 user-initiated page visits to 65,643 distinct URIs and
9,741 different domains. Personal Web usage varied widely in
browsing style and activity: the participants visited 19.5 to 204.8
pages per active day (every day in which at least one event was
3.1 Pre-study challenges
Given the importance of the Web, it might seem surprising that
only so few quantitative long-term studies analyzed the browsing
behavior of Web users. This may be explained by the social and
technical issues we encountered during the preparation of the
study. Today, browsing is considered a personal activity, even if
logging only takes place at the workplace. The Web is now used
for many confidential tasks, such as online banking, shopping or
writing e-mails. After initial informal surveys, it became clear we
had to make use of a capturing system that did not record user-
names or passwords and ignored secure connections. The partici-
pants were also given the option to screen the content of all log
files before transmitting them to us.
Some prospective participants were also concerned that the in-
stallation of such ‘spyware’ might have negative influence on the
stability or performance of their personal computer. These con-
cerns were not unfounded: in one of our pilot studies instrument-
ing the Internet Explorer to record user actions and page requests
led to stability issues when different Explorer versions were used
or new plug-ins were installed – unacceptable for a long-term
study where the browser is used daily as a production tool.
The potential participants of this study used many different
browsers with different browser extensions. In consequence, the
software recording user actions had to be compatible with at least
most of these systems. We opted for a solution based on an inter-
mediary intercepting the traffic between browser and Web. The
release of Firefox 1.0 in 2004 finally provided a platform for in-
strumenting a popular Web browser; its interface is familiar to
users of the Internet Explorer and new security risks of the inter-
net motivated several of our participants to ‘upgrade’. For us, the
open source status of the browser made it possible to implement a
logging mechanism for all user interface actions.
3.2 Browser logging environment
The browser logging environment consisted of two comple-
menting extensions: every participant had an intermediary in-
every page; when executed, this code read several browser
parameters and communicated them to the intermediary. Thus,
detailed knowledge about every link anchor selected, every form
submitted and the current state of the history of the browser win-
dow was obtained. Furthermore, it allowed discriminating all
windows and frames of the client and their current dimensions.
The intermediary also analyzed all transferred documents and re-
corded descriptive data about their length, links and contents.
Technically, this system was based on IBM’s WBI  and the
Scone framework .
15 of the 25 participants used an instrumented version of Firefox
that was modified to record the interaction with all user interface
widgets. These participants were either already using Firefox as
their preferred browser or took the opportunity to switch. Using
exact timestamps, this second clickstream log could be merged
with the navigation log of the intermediary to gain more detailed
and accurate data.
3.3 Data processing and consolidation
The first analyses of the recorded log files showed that serious
data pre-processing was necessary to get valid results, as many of
the entries were not directly related to user actions [cf. 45]. We
found several different reasons responsible for these artifacts:
HTML framesets break the document metaphor – what is visible
for the user does not originate from a single HTML document and
many unusable events are created as every subframe creates a
page request to a different html file. We identified frames by the
name of the frame and the parent window, which was read with
quired not only to collate the requests to one user action, the
events were also often ambiguous, as we could not define which
address was the most important one for a user action: if the user
selected a link in the left navigation frame and a page was loaded
in the right frame, the action occurred on the left page but the
reaction affected the right page with another URI. The interpreta-
tion has consequences on load times, revisitation rate, recorded
document sizes as well as the link positions. Therefore, we exclu-
ded frame pages for most analyses.
Figure 1: Proportions of artifacts for users w/o ad blockers
Another significant problem was caused by advertisements1.
deliberate user actions, events relating to such windows and page
requests were therefore excluded from the study. A statistically
even more relevant advertisement technique is based on iFrames
that allow embedding other HTML pages in a Web document.
Our data showed that iFrames are currently mainly used to
dynamically include advertisements. For the group of participants
that did not apply any kind of ad-blocker (8 users) frame and ad-
vertisement artifacts represented over 28 percent of page requests
(Figure 1). This is remarkable, as it does not even consider online
promotion realized as pure text, embedded images or flash
A third source of non-user initiated page requests were automatic
page reloads, mainly caused by news pages. These became visible
as peaks in the stay time distribution of certain users. In some
1 We identified advertisements by different lists of known servers,
typical URI patterns and equivocal frame names.
contents after a certain interval, in other cases even external appli-
cations like instant messaging agents were responsible for the ar-
tifacts. These contributed nearly four percent of the page requests.
However, the ratio differed severely between participants: some
did not show any periodically reloaded pages, others over 20%.
As became clear during the analysis of the comprehensive
datasets we had gathered, data cleaning and confirmation of user-
initiated events were important to be able to relate recorded
events to user actions. Previous studies did not use similar data
consolidation methods, probably because the amount of such
‘noise’ was lower in the past: in 1995, advertisements were still
hardly known on the Web, and Bruce McKenzie  told us that
even in 2000 the effect of such requests could be neglected.
The prominence of advertisements can safely be interpreted as an
indicator for the increasing commercialization of the Web: sites
providing e-commerce, news and entertainment have become the
most popular destinations, whereas ten years ago Web usage was
focused on information and content delivery . Based on the
collected data, we investigated whether these changes of the Web
also induced changes in user navigation behavior.
4.1 The new character of Web navigation
In this section, we examine the actions that our participants em-
ployed to initiate page visits. We call these events navigation
actions. Apart from selecting links, users can trigger navigation
actions in different ways: entering URIs directly into the address
bar of the browser, using different browser history mechanisms to
revisit pages seen before, or submitting information via forms to
interactive Web services, such as search engine.
The latest reported distributions between the various navigation
actions that are based on long-term data date back to studies from
1995 and 1996. The comparison chart (Table 1) shows some ma-
jor differences, which reflect both the changed nature of the Web
and the way users interact with browser interfaces.
Link following has remained the most common navigation action,
accounting for about 45% of all page transitions. Direct access to
pages via the bookmark menu, bookmark toolbar (which was not
present in previous studies; see Figure 2), home page button or the
address bar has remained stable at about 10% as well. The
detailed Firefox log as well as the interviews revealed, however,
that our users had different preferences to access frequently used
pages: some mainly used the bookmark menu, others solely pre-
ferred the bookmark toolbar and a few had the custom to type the
URI of their favorite pages into the address bar, using its auto-
completion function when available. These different behaviors
show that customization of the interaction with the browser is
necessary. On the other hand it also indicates that none of the cur-
rent revisitation tools is entirely satisfying [1; 20].
The comparison chart shows a major increase in navigation ac-
tions that lead to opening a new browser window. In the mid-
nineties, this event accounted for less than 1% of all navigation
actions, compared to over 10% nowadays. However, while for-
merly only the explicit action of opening a new window using the
associated menu item was registered2, in this study other actions
2 This follows from the much higher number of ‘close window’
and ‘exit program’ than ‘new window’ events reported in .
could also result in opening a new browser window. These actions
include following hyperlinks with target="_blank" as an attri-
bute, starting the browser manually or from other applications and
the using the ‘open link in new window’ or ‘open link in new tab’
entries of the browser’s context menu (Figure 3). Nevertheless,
this confirmed that it has become common behavior to open more
than one window while browsing the Web.
Accounting for over 15% of all navigation actions, form submis-
sion has become a key feature of user navigation as well, as it is a
required interaction mechanism with service-oriented Web sites.
43% of all form submissions involve queries to search engines,
followed in popularity by an online dictionary and travel planners.
By contrast, the share of back button actions has dropped from
over 30% in the mid-nineties to less than 15% presently. This
number includes backtracking multiple steps via the back button’s
pull-down menu, which contributed less than 4% to all back-
tracking actions. The browser history is not specifically listed in
the comparison chart, as it is hardly used – merely 0.2% of all
page requests were initiated from the browser history. Only two
of our twenty-five participants stated to use it from time to time,
while ten participants even weren’t aware of the function at all.
The reduced usage of the back button, in combination with an in-
crease of ‘forward navigation actions’ – following links, submit-
ting forms and opening new windows – might indicate that users
return less frequently to previously visited pages. However, the
recurrence rate – the percentage of page revisits  – decreased
to a much lesser extent; from about 60% to 46% (excluding frame
pages; see above, ). One explanation is that most sites now
offer structural links on every page that allow returning to the
home page or a landmark page without using the back button.
However, there might also be a relation with the increased amount
of submit and new window actions. This issue will be explored in
the following two subsections.
3 We recalculated the values of  and , as their notion of
navigation action differed from each other. To make all values
comparable we applied the definition used in this study.
Form submission and backtracking
The increased number of form submissions confirms another
change of the Web: the move from a hypertext information
system with mainly static pages to a hybrid between ‘classical
hypertext’ and service oriented interactive systems, such as search
engines, dictionaries and travel planners. The latter category of
sites is often more similar to desktop applications than to
information-centered hypertext: whereas navigation in hypertext
involves orienteering behavior with frequent backtracking,
interactive applications are mainly used for ‘getting things done’.
This would imply that backtracking is less prominent during these
activities. In order to confirm this hypothesis, we compared the
backtracking usage of the top third form submitters of our
participants with the remaining participants. The frequent
submitters used the back button less frequently (9.2%) than the
others (16.2%), a difference that is marginally significant
Dynamic, interactive pages pose several challenges to the
browser’s history mechanisms. First, the browser history does not
take form submissions using the http POST method into account.
Unless the URL of the resulting page explicitly contains the
issued parameters, users cannot revisit earlier created documents
such as travel plans without going through the process of entering
the data again. Once the browser window is closed, the travel plan
is lost. The same problem arises for documents that users might
want to keep for future reference, such as order confirmations and
flight reservations. Unlike in static hypertext, these pages are
volatile, even if they contain information that will remain most
relevant in the near or more distant future. Whereas users can
save or print the information, most participants reported that they
almost never did so. The Internet Explorer for Mac OS X features
the Scrapbook, which provides an integrated interface for storing
an exact copy of the Web page as it appears in the browser win-
dow. With the advent of service-oriented sites and volatile pages,
similar functionality might be needed in other Web browsers as
well. Travel plans, flight reservations and order confirmations
should be treated as documents; context-sensitive functionality for
storing, retrieving, opening and printing – like in regular office
applications – appear to be essential in these situations.
To follow the analogy with office applications even further: as
mentioned earlier in this section, the concept of hypermedia navi-
gation is often replaced by a concept of interaction with an appli-
cation. Hence, navigation tools such as the back button lose their
original meaning in these contexts. While using an interactive
Web service, the back button bears more similarity to the undo
button: users press back to correct errors. To avoid potential dis-
ruption of the interaction, some online services disable the use of
the back button by opening a pop-up window without navigation
toolbars for sequences of interactive forms, or they explicitly ad-
vice the user not to use the back button.
In conclusion, browser interfaces do not provide appropriate
functions for service-oriented sites, although these sites play a
prominent role in Web usage. We think that one major challenge
for the next generation of Web browsers is to reconcile the two
different Web usage contexts – hypermedia navigation and inter-
action with Web-based services.
Windows, tabs and backtracking
As reported in the beginning of this section, our participants
tended to use multiple windows to a large extent. The strategy of
Table 1: Comparison chart of three long-term studies
Time of study
1994 1995-1996 2004-2005
No. of users
107 23 25
21 35-42 52-195, ø=105
No. of visits
31,134 84,841 137,272
61% 58% 45.6%
45.7% 43.4% 43.5%
35.7% 31.7% 14.3%
- 4.4% 15.3%
0.2% 0.8% 10.5%
12.6% 13.2% 9.4%
4.3% 3.3% 1.7%
1.5% 0.8% 0.6%
- 2.3% 4.8%
opening new windows seems to offer several advantages. Our
users reported that multiple windows allowed them to ‘compare
search results side by side’ and that ‘pages can be loaded in the
background’ while they continue their navigation activities.
Keeping search results and resulting navigation trails in separate
windows also reduces the risk of losing the path to a decisive
page because of backtracking to the result page. Several
participants also had the habit of keeping a browser window with
their favorite news site open in the background.
A comparison of the frequency of backtracking with the usage of
multiple windows or tabs showed a correlation between these two
navigation actions. The group of participants with the top third of
new window events employed the back button to a lesser extent
(10.2%) than the bottom third (16.4%); it is plausible that multi-
ple windows are used as an alternative to backtracking (t=2.509,
p=0.026). In addition to multiple windows, Firefox provides
‘tabbed browsing’ – several pages can be opened simultaneously
in different browser tabs (Figure 3). Six participants who used
tabs frequently, were backtracking less often (9.9%) than the re-
maining seven Firefox users (18.3%) that hardly opened any tabs
(t=2.311, p=0.038). One participant explained he used ‘new tabs
for closely related tasks and new windows for parallel tasks’.
A more disturbing consequence of the use of multiple windows is
that it disrupts the concept of the back button. Its principal func-
tionality is to return to recently visited pages. If users followed
trails in multiple windows or tabs, the recent visit history is split
into separate stacks, with no temporal relation. Moreover, each
individual stack is does not include actions from the originating
window. Hence, users need to remember what actions they per-
formed in which window or tab in order to relocate a previously
visited page. This places a high cognitive burden on the user, in
addition to the already demanding task of keeping track of their
location in the Web . Handling multiple windows in infor-
mation systems was already reported to cause disorientation in
pre-web studies . The above concerns were confirmed by our
participants; several said that they find many open Web docu-
ments hard to manage, in particular because the page titles dis-
played in task bar and tabs are often not helpful.
The more prominent use of multiple windows requires a major
rethinking of the history mechanisms of browsers. It provides new
challenges to the often criticized [6; 12; 21] yet often used back
button. A linear history of most recent revisits, as proposed by
, does not reflect the character of parallel trails and the un-
related back button stacks do not take the temporal relations
between the trails into account.
4.2 The velocity of Web navigation
The speed of interaction with the Web browser is another aspect
of Web navigation: how much time do users spend on Web pages,
i.e., how much time do they take to read the page and think about
the available options, before they perform their next action? Al-
though the time between page requests can be gained from server
logs  and the browser history , the data recorded with a
client side logging software is more exact. Our software recorded
the time between the display of the first parts of the HTML docu-
ment and any subsequent navigation action in the same window
that would lead to the request of another page. In consequence,
delays – such as the time before the browser begins to load a page
– could be differentiated from the stay time. Navigation actions
that did not lead to a new request to the same site were also con-
sidered, like the selection of an external link, as well as back-
tracking – which is usually hidden in server logs since the page is
loaded from the browser’s cache, and leaving a page by closing it.
The capturing software did also distinguish between multiple
windows and tabs, so it could be identified, when a user opened
several pages at once from a hub page, but read them one after the
other. Although this method removed incorrect values for the time
a page is opened in a browser, there will be a bias towards long
stay times, as open windows that currently do not have the user’s
attention could not be identified and excluded.
This study confirms the rapid interaction behavior with heavy
tailed distribution already reported by previous studies [3; 7; 11].
Our participants stayed only for a short period on most pages:
25% of all documents were displayed for less than 4 seconds and
52% of all visits were shorter than 10 seconds (median: 9.4s).
However, nearly 10% of the page visits were longer than two
minutes. Figure 4 shows the distribution of stay times grouped in
intervals of one second. The peak value is located at stay times
between 2 and 3 seconds; they contribute 8.6% of all visits.
We first assumed that most of these short and very short stay
times represented revisits, e.g., visits to pages that had been seen
recently or that were used frequently and therefore well known,
like the home page of the browser. To analyze how much time
users take to read new Web documents, all revisited pages were
Figure 2: Bookmark toolbar and browser history in sidebar
Figure 3: Tabbed browsing: opening a new tab from a link
excluded from the statistics. The effect on the distribution of stay
times was not as strong as expected (Figure 4): still over 17% of
all new pages are visited for less than 4 seconds, nearly 50% are
shown for less than 12 seconds and 11.6% are displayed for more
than 2 minutes (median: 12.4s). However, a fifth of the 11.6%
were visits of over 30 minutes to up to 5 days – most of these
events are most likely created by unattended browser windows
that were left open in the background of the desktop.
The tendency for very short page visits on the Web might have
two reasons: either it expresses a cursorily and scanning usage
behavior or it might characterize that many of the visited pages
offer only little information and few navigational options. To
verify this, the average number of words and links of the docu-
ments was calculated and compared with the stay times.
These results are based on nearly 60,000 first-page visits. The
average number of words per page (only depicted text, not con-
sidering any markup code or any embedded objects or graphics) is
551 words (σ=811)4. The page stay times are dependent on the
page size, but less than expected: pages visited for less than 12
seconds (they contribute about 50% of all requests) had an aver-
age number of 430 words. This is significantly lower than the
mean size of documents with a longer retention time (t=36.197,
p=0.000), but it is apparent that no person can read a full page of
this length that quickly. Figure 4 (upper graph) illustrates the
average number of words per page grouped in intervals of 2s
staying time. Such a difference was also found for the number of
navigational options per page (Figure 5). On average all visited
pages had 53 hyperlinks5 (σ=58). For pages with a staying time of
less than 12s the average number of links was 46 and significantly
lower than for the remaining documents (t=30.659, p=0.000).
In consequence our participants often did not take the time to
completely read every page, but they regularly just seemed to
glimpse over most of the information offered, before they perform
their next navigation action. Such a scanning behavior of Web
4 Outliers were removed (using a 3σ limit), as very few Web
pages were atypically long and biased the sample. Average with
outliers: 648 words (σ=2342).
5 Again, outliers were removed. All visited pages had an average
of 61 hyperlinks (σ=122).
users was already reported by  and  who observed it at
several controlled Web usability studies. The data of this long-
term study supports these results, indicating that the ‘scannability’
of information and hyperlinks as well as their intelligibility seem
to be essential for the usability of Web pages (see Section 4.3).
Does the responsiveness of the Web suffice?
The participants of this study viewed many Web pages only for a
very short time before taking the next action. This rapid inter-
active behavior requires a system that reacts quickly, too. Though
the performance of the Web was often criticized in the nineties
and even called ‘the most common usability problem of the Web’
, this shortcoming was less of a topic for the last five years.
While the digital divide excludes many low-income families and
the citizens of developing countries from the resources offered by
internet and Web, a continually increasing number of users have
broadband access . It seems the Web has either become re-
sponsive enough to meet its users’ needs or they have got accus-
tomed to inevitable delays, as new studies show that people are
now more concerned with quality, privacy and security on the
Web [8, 44]. We recorded transfer delays to estimate if the Web
was fast enough to meet current user interface standards.
As the application areas of the Web changes from an information
resource to an online application system, the performance re-
quirements for hypertext systems as well as office software
should be met. Many studies have confirmed a maximum reply
time of 2 to 4 seconds; otherwise productivity degrades
significantly [37; 16, p.74; 39, p.297].
Our participants had different types of internet connections. 14
participants made use of fast leased lines (at least OC-3), eight
people used ADSL broadband access and three had only an ISDN
dial-up connection. The logging software6 recorded two values
within the browser for every page request: First, the delay be-
tween the user action that led to the new page request and the start
script took timestamps of user and browser events, allowing us
to get the actual response times as perceived by the participants
. This data was transmitted to the intermediary and stored in
the event log.
0s4s 8s 12s 16s20s 24s 28s 32s36s 42s
Average Number of Words Average Number of Links
Figure 5: Correlation between stay time and page contents
0s 2s 4s 6s 8s 10s 12s 14s 16s 18s 20s 22s 24s 26s 28s 30s
Average stay times for all pagesStay times for first-time visits
Figure 4: Distribution of stay times for all participants
of the page rendering was taken; second, the time to download the
entire document including all embedded objects was registered.
The delay between a user action to request a new page and the
arrival of the first data packages at the browser is critical, as the
user has to pause and wait until this process is finished, before he
may continue to use that browser window. We regarded only first-
time page visits, as revisited documents are usually loaded from a
proxy or the browser cache. The distribution (Figure 6, upper
graph) shows that most requests are answered quite quickly: the
median delay until the browser received the first parts of the
document was 1.0 second. However, 90% of all replies took
longer than 0.7 seconds. Consequently, data processing of the
browser and the three way handshake of TCP/IP are already
limiting factors for the performance of the Web. Furthermore,
over 9% of the requests could not be answered within 4 seconds,
and about 4% took more than 10 seconds or were not answered at
all. These long delays are not only caused by low bandwidth con-
nections and slow responding servers, due to the way the times
were detected in the browser, they also stand for requests that led
to an erroneous response (for instance caused by a removed
document). 4% is actually the average number of broken links on
the Web .
0s 1s2s3s 4s5s6s7s 8s 9s10s 11s12s
Delay New Pages (only RTT) Delay New Domains (with DNS)
Figure 6: Response times for new pages and sites
A user request to a new server requires that the domain name is
resolved, making these requests presumably slower. The lower
graph of Figure 6 shows the average response times of all first-
time visits to Web servers. The median delay was already 1.7 sec-
onds and even 7% were not properly answered within 10 seconds.
This indicates that transfer delays as well as broken links are a
more severe problem for site-external than local references.
The ‘pure download time’ for Web pages, i.e., the time from the
arrival of the first packet of the HTML document to the last part
of every embedded object, shows a quite similar characteristic:
49% of all documents were downloaded in less than one second,
with a tendency to very short times, and nearly 86% were fully
transmitted in less than 4 seconds (Figure 7). However, this does
also mean that over 14% of the page transfers could not be com-
pleted in 4 seconds.
As this result might be distorted by the three ISDN users, the
download times were discriminated by bandwidth (Figure 7). Ex-
pectedly, the performance of the Web is poor for ISDN users: less
than 60% of the documents could be completely downloaded
within 4 seconds. But also for broadband users, the delays were
often insufficient: 9% (leased line) or 16% (ADSL) of the trans-
fers were not completed in 4 seconds – even not considering the
additional median round trip and processing time of one second.
At first glance, a delay of about 1 second before the browser starts
to display the new page seems to be acceptable; however, when
the rapid navigation behavior of our participants and the require-
ments of interactive online applications are considered, this is
comparatively long and may certainly have negative influence on
the overall user performance. Especially external links are poten-
tially critical, as they bear longer delays and more erroneous ref-
erences. Further research seems to be necessary.
4.3 Within-page navigation
If a Web page is too long to be displayed on one screen, the user
has to navigate on the page by scrolling it. Scrolling is often con-
sidered problematic, as it can result in user disorientation: the
reader may lose track of the context as the main headers, the site
identifier and the main navigation elements move off screen. Fur-
thermore, scrolling increases the cognitive burden: while long
pages require the reader to remember information that scrolled off
the screen, short pages allow comparing all available options side
by side. Therefore, especially for entry pages and navigation
pages guidelines recommend to fitting the page on one screen and
show all options immediately [24; 30].
On the other hand, for content pages long documents can also
bring advantages, as they can be read and printed without the
need to flip from one page to another. Still, wide pages that requi-
re horizontal scrolling should be avoided for any kind of Web
document, since they bear the risk that users have to move their
viewport in two dimensions, wide text lines have a low readabili-
ty, and the printout of these pages may be cropped [24; 28].
The short stay times on Web pages seem to justify short, non-
scrolling pages; they pose the question whether users take the
time to scroll at all. As scrolling is especially critical for naviga-
tion pages, we concentrated on pages that were used to navigate
to another page and analyzed all clicks on hyperlinks as they
comprise the most important navigation action on the Web.
A comparison of the link click positions and the browser viewport
size shows that most links (76.5%) were selected within the re-
gion visible on load time (Table 2). Although users hardly scroll
horizontally to select a link (altogether 0.4%), over 23% of the
link clicks were below the initially visible region. Even for pages
with stay times below 12 seconds, over 20% of the selected links
required scrolling. Actually, the number of clicked links ‘below
0s1s2s 3s 4s5s6s7s 8s 9s 10s11s 12s
All participantsISDN 64kBitADSL 2MBit Leased Line
Figure 7: Download times by bandwidth
the fold’ is higher than expected considering the short median
stay time on pages.
However, the position of selected links is not only influenced by
the scrolling habits of users, but also by the location of the avail-
able links. To get an overview of the navigation activity in the
different screen regions, a map of all link clicks was created by
grouping them in sections of 40 by 40 pixels. From over 27,000
recorded clicks, 93% were within an area of 1040?1600 pixels,
which is depicted in Figure 8.
The most actively selected area is located in the upper left corner
of the map: over 45% of all user clicks occur in a region of the
browser window that is slightly larger than the upper left quadrant
of the initially visible page area (520?400 pixels). Furthermore,
in Figure 8 the horizontal and vertical navigation bars that provide
the main structural hyperlinks on most major sites become visible,
albeit the emphasis is on the left part of the horizontal and the up-
per part of the vertical bar. It should be noted this does not mean
that these areas are generally suited best to place links, yet pages
with a matching layout will meet the expectations of many users
and increase the consistency of the Web.
The image shows an unexpectedly active area in the lower part of
the documents, at about 600?1000 pixel and below, which re-
quired scrolling on all of our participants’ screens. It turned out
that these clicks are mainly caused by Google’s placement of the
‘next page’ link. In fact, this detail indicates how often users have
to scroll on the Web, as all popular search engines provide result
lists that do not fit on a single screen – if we remove all search
engine pages from the dataset, the vertical scroll ratio drops from
23% to 18%. Without taking transfer time into account, requiring
users to both scroll and to flip through pages seems to be in-
The real browser real estate
Web page optimization for the users’ rapid navigation behavior
includes incorporating scannability and providing all relevant in-
formation at a single glimpse. Creating Web pages that do not re-
quire scrolling, however, requires knowledge of the available
browser real estate. Although Web content should in principle be
accessible to all people with different abilities and arbitrary hard-
ware , for an aesthetic appearance device-specific designs are
often inevitable. Particular style sheets should not require par-
ticular screen dimensions, but in practice, style sheets and graphi-
cal elements (like bitmap graphics) need to consider the available
space of the browser. Thus, many Web authors try to optimize
layout and design for a specific resolution.
Over the last years, the average screen resolution of personal
computers has increased . Until 2004, many experts recom-
mended to base Web design on a resolution of 800?600 pixels,
whereas recently the migration of the layout for a resolution of
1024?768 pixels is being recommended7 more often. We wanted
7 Experts who support ‘wide screen designs’ are ,  and for
to find out whether the full resolution is really available for Web
pages, or if technical or personal reasons limit the browser view-
port. Due to browser internals, we could only record the browser
viewport size for 20 participants. The size was recorded in more
than 12.000 instances, usually after selecting a link. Frame pages
were again excluded, as their sub-pages might adulterate the sta-
tistics. All participants used a screen resolution of at least
1024?768 pixels, twelve even had a higher resolution and three
made use of two displays.
We could identify two groups: while eleven participants had the
browser in full screen mode most of the time, nine participants
preferred a smaller window size for at least half of the recorded
time. However, the users of a maximized browser window also
rarely had the full desktop resolution available: office toolbars,
instant messaging clients, browser toolbar extensions as well as
browser tabs and the side bar (Figure 2) took some of the vertical
and horizontal space for most of them. Furthermore, some par-
ticipants preferred to maximize the browser manually, leaving a
border of several pixels around the window unused.
The nine participants with smaller browser windows (two of them
with a screen width of 1024 pixels) left on average about 160 pix-
els of horizontal and 170 pixels of vertical space unused – scroll-
bars, pull-down menus, toolbars and the windows task bar already
considered. For the users with a screen resolution of 1024 pixels,
the average available document width was only about 890 pixels.
They stated to prefer the windowed mode for several reasons: it
permitted them to view and select other windows directly on the
screen making the organization of several applications less com-
0 - 39
120 - 159
240 - 279
360 - 399
480 - 519
600 - 639
720 - 759
840 - 879
960 - 999
1080 - 1119
1200 - 1239
1320 - 1359
1440 - 1479
1560 - 1599
0 - 39
80 - 119
160 - 199240 - 279 320 - 359400 - 439480 - 519560 - 599640 - 679 720 - 759800 - 839880 - 919960 - 999
Figure 8: Link activity areas of Web users.
Table 2: Location of selected links
Visible Area Right of Visible Area
Below Visible Area
plicated. Furthermore, a narrower window would improve the
readability of many documents as the lines of text were shorter.
Consequently, accessible sites should consider that people have
different preferences using their desktop system and resizing their
windows. If sites do not want to displease their visitors by forcing
them to maximize their browser window or scroll horizontally,
designers should not count on having exclusive rights to the
screen real estate: flexible layouts leaving at least 15% of the
screen width obtainable should instead be applied.
5. LIMITATIONS OF THE STUDY
Though the recorded data of this study is extensive and detailed, it
has its limits, as it misses contextual information. The extent of
logging was restricted technically, as data capture was limited to
the browser, ignoring related software that was used in conjunc-
tion with the Web client, such as word processors, e-mail agents
and other office applications. Furthermore, the data of clickstream
logs have a limited expressiveness, as aims and tasks of the users
often stay below the surface. This makes their contextual inter-
pretation inherently difficult and additional qualitative informa-
tion is needed to support a detailed task-related evaluation of the
data. The two 90-minute interviews conducted at the beginning
and end of the study could only deliver scarce data for a substan-
tial qualitative analysis.
Another critical aspect of such a study concerns social and profes-
sional differences in user groups. Although we tried to recruit
many different participants, all were frequent computer users with
long internet experience. Still, the variance in the captured data
was fairly large for almost all aspects of navigation: the number
of visits, page vocabulary and use of search engines differed be-
tween the individuals. Also, the applied navigation habits, espe-
cially to directly access documents and to revisit pages varied.
However, the remarkable differences in this small participant
group did already reveal that Web browsers are used with various
personal preferences and that individual users have particular de-
mands. Web browsing is no longer simply navigation – and to a
decreasing degree it is pure information and document retrieval.
This should be considered for the design of future Web clients,
Web sites and Web applications.
This paper presents results of an extensive long-term study that
captured the Web browsing behavior of 25 participants with di-
verse backgrounds and tasks. Although some results from former
studies could be confirmed, we found evidence for a change of
interaction with the Web. A strong increase in the proportion of
submit events indicates the rising number of dynamic Web pages
and ‘Web applications’; the increased number of new window
events suggests that interaction with the Web client is changing
from single-window hypertext navigation to a new mode where
several paths are followed in parallel. Furthermore, some browser
windows stay open for a long time or are dedicated for special
online services like a news site or an online dictionary. Since
navigation support of current browsers is still very similar to the
early days of the Web, new problems surface: backtracking and
history were not designed for dynamic pages and online appli-
cations with volatile contents; the concept of the back button fails
for users of multiple windows or tabs as every document area has
its own history stack. In consequence, users are faced with a new
cognitive overhead when they browse the Web.
Our results confirm that browsing is a rapidly interactive activity.
Even pages with plentiful information and many links are regu-
larly viewed for a brief period – an interesting background for
Web designers, who could focus on offering concise pages that
load fast. Interface standards for the Web would help to make
navigation on unfamiliar sites easier and quicker [15; 29]. Also,
response times are often still not appropriate and Web developers
should consider the additional delay before the browser starts to
display a document when they estimate download times.
The analysis of link click positions shows that users do scroll fre-
quently – even on navigation pages and on pages they visit only
for a short period. Still, most selected links reside in the upper left
quarter of the browser window. Placing the most important links
in this area will increase consistency with this de facto standard.
To avoid scrolling pages, Web designers need to consider the
limitations of browser real estate even for users with a high screen
resolution. If they make use of the full resolution of 1024?768,
the resulting design restrains many users who might prefer to use
their Web client in windowed mode or concurrently use tools that
reduce their available screen space.
In conclusion, we see two challenges for the future: on the one
hand, rapid interaction should be supported by user interface
standards for Web pages and Web applications that meet the
users’ expectations. On the other hand, browsers need to become
more flexible and should be able to adapt to the type of Web site,
the habits of the user and her tasks. Further research has to target
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