The pragmatics of hashtags: Inference and conversational style on Twitter

•I examine the pragmatic function of hashtags (#) on social networking site Twitter.•Hashtags have developed beyond their search function to convey context information.•Content in hashtags guides the derivation of both explicit and implicit meaning.•Hashtags help facilitate the use of an informal interpersonal style online.

This paper considers the pragmatic contribution of hashtags on the social networking site Twitter. Taking a relevance-theoretic perspective, I argue that hashtags contribute to relevance by adding a layer of activation to certain contextual assumptions and thus guiding the reader's inferential processes. The information contained in a hashtag may guide the hearer in the derivation of both explicitly and implicitly communicated meaning, and may also have stylistic consequences. Twitter facilities one-to-many, asynchronous communication, and so tweeters are unlikely to be able to assume that they share contextual assumptions with all or any of their audience. By allowing tweeters to make their intended contextual assumptions accessible to a wide range of readers, hashtags facilitate the use of an informal, casual style, even in the unpredictable and largely anonymous discourse context of Twitter.