A speech act in linguistics and the philosophy of language is an utterance that has performative function in language and communication. According to Kent Bach, "almost any speech act is really the performance of several acts at once, distinguished by different aspects of the speaker's intention: there is the act of saying something, what one does in saying it, such as requesting or promising, and how one is trying to affect one's audience." The contemporary use of the term goes back to J. L. Austin's development of performative utterances and his theory of locutionary, illocutionary, and perlocutionary acts. Speech acts are commonly taken to include such acts as promising, ordering, greeting, warning, inviting and congratulating.
Speech acts can be analysed on three levels:
The concept of an illocutionary act is central to the concept of a speech act. Although there are numerous opinions regarding how to define 'illocutionary acts', there are some kinds of acts which are widely accepted as illocutionary, as for example promising, ordering someone, and bequeathing.
Following the usage of, for example, John R. Searle, "speech act" is often meant to refer just to the same thing as the term illocutionary act, which John L. Austin had originally introduced in How to Do Things with Words (published posthumously in 1962). Searle's work on speech acts is also commonly understood to refine Austin's conception. However, some philosophers have pointed out a significant difference between the two conceptions: whereas Austin emphasized the conventional interpretation of speech acts, Searle emphasized a psychological interpretation (based on beliefs, intentions, etc.).
According to Austin's preliminary informal description, the idea of an "illocutionary act" can be captured by emphasizing that "by saying something, we do something", as when someone issues an order to someone to go by saying "Go!", or when a minister joins two people in marriage saying, "I now pronounce you husband and wife." (Austin would eventually define the "illocutionary act" in a more exact manner.)