Speech Act is a technical term in linguistics

Linguistics

Linguistics is the scientific study of human language. Linguistics can be broadly broken into three categories or subfields of study: language form, language meaning, and language in context....

 and the philosophy of language

Philosophy of language

Philosophy of language is the reasoned inquiry into the nature, origins, and usage of language. As a topic, the philosophy of language for analytic philosophers is concerned with four central problems: the nature of meaning, language use, language cognition, and the relationship between language...

. The contemporary use of the term goes back to John L. Austin

J. L. Austin

John Langshaw Austin was a British philosopher of language, born in Lancaster and educated at Shrewsbury School and Balliol College, Oxford University. Austin is widely associated with the concept of the speech act and the idea that speech is itself a form of action...

's doctrine of locutionary

Locutionary act

In linguistics and the philosophy of mind, a locutionary act is the performance of an utterance, and hence of a speech act. The term equally refers to the surface meaning of an utterance because, according to J. L...

, illocutionary

Illocutionary act

Illocutionary act is a term in linguistics introduced by John L. Austin in his investigation of the various aspects of speech acts. We may sum up Austin's theory of speech acts with the following example...

, and perlocutionary act

Perlocutionary act

A perlocutionary act is a speech act, as viewed at the level of its psychological consequences, such as persuading, convincing, scaring, enlightening, inspiring, or otherwise getting someone to do or realize something...

s. 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: A locutionary act

Locutionary act

In linguistics and the philosophy of mind, a locutionary act is the performance of an utterance, and hence of a speech act. The term equally refers to the surface meaning of an utterance because, according to J. L...

, the performance of an utterance: the actual utterance and its ostensible meaning, comprising phonetic, phatic and rhetic acts corresponding to the verbal, syntactic and semantic aspects of any meaningful utterance; an illocutionary act

Illocutionary act

Illocutionary act is a term in linguistics introduced by John L. Austin in his investigation of the various aspects of speech acts. We may sum up Austin's theory of speech acts with the following example...

: the semantic 'illocutionary force' of the utterance, thus its real, intended meaning (see below); and in certain cases a further perlocutionary act

Perlocutionary act

A perlocutionary act is a speech act, as viewed at the level of its psychological consequences, such as persuading, convincing, scaring, enlightening, inspiring, or otherwise getting someone to do or realize something...

: its actual effect, such as persuading, convincing, scaring, enlightening, inspiring, or otherwise getting someone to do or realize something, whether intended or not (Austin 1962).
The concept of an illocutionary act

Illocutionary act

Illocutionary act is a term in linguistics introduced by John L. Austin in his investigation of the various aspects of speech acts. We may sum up Austin's theory of speech acts with the following example...

 is central to the concept of a speech act.