Speech Acts

Speech acts can be analysed on three levels:

A locutionary act, 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: the pragmatic 'illocutionary force' of the utterance, thus its intended significance as a socially valid verbal action (see below);
a perlocutionary act: its actual effect, such as persuading, convincing, scaring, enlightening, inspiring, or otherwise getting someone to do or realize something, whether intended or not (Austin 19)

Source: http://en.wikipedia.org/wiki/Speech_act

For more information, you can also check: Speech Act Theory