... Because they fit well with the social Web's general principle of sharing and participating, crowdsourced tags quickly established themselves as one of the major forces for converting the static Web into a participatory information space (Ding, Jacob, Yan, George, & Guo, 2009). Consequently, there is a considerable amount of work in the literature focusing on various aspects of tags and tagging behaviors, which include tagging motivation (Ames & Naaman, 2007;Nov & Ye, 2010;Strohmaier, Körner, & Kern, 2010), navigation (Chi & Mytkowicz, 2007;Helic, Trattner, Strohmaier, & Andrews, 2010), and search (Bischoff, Firan, Nejdl, & Paiu, 2008;Heymann, Koutrika, & Garcia-Molina, 2008;Trattner, Lin, Parra, & Brusilovsky, 2012). Readers who want to know more about this topic should read Gupta's overview article (Gupta, Li, Yin, & Han, 2011) and Smith's book (Smith, 2007). ...