The aim of the present study is to explore whether traditional discourse units are valid
for the analysis of instant messaging (IM) conversations in Spanish. Corpus-based
techniques were applied to a 176000 words corpus of Whatsapp interactions in order to
compare their features with those of written/spoken texts and of other new forms of
communications in Internet. The findings show that we do find relevant differences that
affect both the structure of the interaction and how we define the interaction itself.
Results indicate that conversations with IM have fuzzy limits, usually occur
simultaneously to other interactions, and are multimodal. The findings suggest that units
of analysis should be revised not as a variation of traditional written/spoken texts, but as
a different class of interactions.