This document distinguishes between language systems and language skills. It discusses the key components of language systems, including phonology, lexis, grammar, morphology, syntax, and functional and situational aspects. It also outlines the four main language skills - listening, speaking, reading, and writing - and how they relate to each other as receptive or productive skills involving spoken or written communication. The document emphasizes that an integrated approach to teaching language systems and skills is important for effective language learning and communication.