Informal and formal language

Formality tells peopel when to use formal language and informal language.

Informal are times when rules and politenesse don't have to be followed. For informal examples: G, wasssup, and yo. 

Formal language are times when rules and politeness need to be followed. Some examples for formal language: greetings, hello, want to and do not.

Sometimes formal situations can be like informal situations, for example: Having a meeting at the park, playing a game at a meeting.