In linguistics, a phatic expression is one whose only function is to perform a social task.
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 be polite in response to a gift.
Similarly, to ask, "How are you today?", is usually a rhetorical phatic question which is an automatic response resulting from meeting someone. Although there are times when, "How are you today?" is asked in a sincere, concerned manner and does in fact anticipate a detailed response from the person met, which should be inferred by the inflection in the delivery of the expression, this is often contrary to some peoples perceived need to respond in verbose utterance as to the exact nature of their present ills, when the question was actually a rhetorical phatic!
The utterance of a phatic expression is a kind of speech act.
See also etiquette.
