Summary. According to the British Linguist J.L. Austin, two different parts of speech can be distinguished: The constantives (ideas that describe) and the performatives (ideas that command). Constantives can be understood as sentences that describe if something is true or false(statements). On the contrary, performatives are sentences that denote action. These sentences depend on felicity conditions, which are rules under which they can be enacted. Basically, these rules state that performatives should be authoritative,clear, understood and able to be executed in order to denote action. However, gathering these conditions does not necessarily imply that performatives would be implicity followed. It is also worth mentioning that there are some words (like "recycle") that ARE actions(the actions include apologising, promising,ordering,warning). These words are known as Speech acts.