There are two types of grammars: descriptive and prescriptive. Descriptive grammars represent the unconscious knowledge of a language. English speakers, for example, know that "me likes apples" is incorrect and "I like apples" is correct, although the speaker may not be able to explain why. Descriptive grammars do not teach the rules of a language, but rather describe rules that are already known. In contrast, prescriptive grammars dictate what a speaker's grammar should be and they include teaching grammars, which are written to help teach a foreign language.