1. language is a system: it has different linguistic levels (phonological, related to phonemes, intonation and rhythm; lexical semantic, which have to do with lexis, that is, the words, and their meaning (semantics); syntactical, that is, the rules of grammar; discourse, written language; conversation, that is, the characteristics of spoken discourse (turn-taking, use of words, etc.); sociolinguistic (social factors, such as educational level, age, ethnic, sex, etc.);