The sociolinguistic variables are cultural context, register, audience, purpose, and situational context. You can remember them with “CRAPS”.
cultural context
Different cultures have different words for things, reflecting their unique experiences and stuff. Even within Australia, people from different places use English differently.
register
A register is a language variation across subsystems like lexicon, grammar and pronunciation, used for a particular situation.
A formal register means more formal words and less contractions.
audience
The audience significantly influence your language choices. Obviously.
purpose
The purpose is reason why you are communicating. What are you trying to achieve?
situational context
The situational context is the environment in which you communicate.
You would speak differently at a funeral than you would at a birthday party. Hopefully.