This document discusses how language varies based on social and geographical factors. It explores differences in dialect, accent, vocabulary, grammar, and pronunciation between varieties of English like British English, American English, and Australian English. Language variation exists across registers that are conditioned by their uses, like legal or religious registers, and between formal and informal styles of speech. Communities that share linguistic norms and rules for language use are called speech communities, and a speaker's communicative competence involves their underlying knowledge of a language's rules and how to use them.