In linguistics, a phatic expression // is communication which serves a social function such as small talk and social pleasantries that don't seek or offer any information of value. For example, greetings such as "hello" and "how are you?" are phatic expressions.
The term phatic communion ('bonding by language') was coined by anthropologist Bronisław Malinowski in his essay "The Problem of Meaning in Primitive Languages", which appeared in 1923 a supplementary contribution to The Meaning of Meaning by C. K. Ogden and I. A. Richards. The term "phatic" means "linguistic" (i.e. "by language") and comes from the Greek φατός phatós ("spoken, that may be spoken"), from φημί phēmí ("I speak, say").
Besides speech, in the digital world, phatic expression can also cover digital interactions. For example, liking someone's social media post can communicate social approval and as a consequence build rapport.
In phatic communion, speech acts are not communicative, since no content is communicated. According to Malinowski even such apparently "purposeless" speech acts as polite small talk, like "how are you?" or "have a nice day," even though its content may be trivial or irrelevant to the situation, perform the important function of establishing, maintaining, and managing bonds of sociality between participants. 
In Roman Jakobson's work, the 'phatic' function of language concerns the channel of communication, for instance when one says "I can't hear you, you're breaking up" in the middle of a cell phone conversation (obviously, not Jakobson's example). This usage appears, for instance, in research on online communities and micro-blogging.
For example: "You're welcome" is not intended to convey the message that the hearer is welcome; it is a phatic response to being thanked, which in turn is a phatic whose function is to acknowledge the receipt of a benefit.
Similarly, the question "how are you?" is usually an automatic component of a social encounter. Although there are times when "how are you?" is asked in a sincere, concerned manner and does in fact anticipate a detailed response regarding the respondent's present state, this needs to be pragmatically inferred from context and intonation.
The following is a specific example of the former: a simple, basic exchange between two acquaintances in a non-formal environment.
- Speaker one: "What's up?" (US English. In UK English this means "is there something wrong?")
- Speaker two: "Hey, how's it going?"
- Speaker one: "Alright?" (UK English. In US English this means "is there something wrong?")
- Speaker two: "You alright."
Neither speaker expects an actual answer to the question. Much like a shared nod, it is an indication that each has recognized the other's presence and has therefore sufficiently performed that particular social duty.
In Japanese, phatic expressions play a significant role in communication, where they are referred to as "aizuchi."
- Malinowski, B. (1923), "The Problem of Meaning in Primitive Languages", in Charles K. Ogden and Ian A. Richards, The Meaning of Meaning, London: Kegan Paul, Trench and Trubner, pp. 296–336
- "Phatic", Oxford Living Dictionaries: British & World English, Oxford University Press, n.d., retrieved October 25, 2016
- Haberland, H. (1996) "Communion or communication? A historical note on one of the 'founding fathers' of pragmatics", in Robin Sackmann (ed.), "Theretical linguistics and grammatical description", 163-166, Amsterdam: Benjamins
- Malinowski, B. (1923) "The Problem of Meaning in Primitive Languages”, in: Charles K. Ogden and Ian A. Richards, The Meaning of Meaning, 296-336, London: Kegan Paul, Trench and Trubner
- Makice, Kevin (2009). "Phatics and the design of community". Proceedings of the 27th international conference extended abstracts on Human factors in computing systems. Boston, MA, USA.
- pear analytics (2009). "Twitter Study – August 2009, Whitepaper".
- "Teach Yourself Linguistics", by Jean Aitchison, ISBN 978-0-340-87083-9