This document discusses Systemic Functional Linguistics (SFL), an approach to language developed by M.K.A Halliday in the 1960s. SFL considers language as a social semiotic system based on five principles: social semiotics, language as a resource, text rather than sentences, text and social context, and construing meaning. SFL analyzes language through three metafunctions - ideational meaning, interpersonal meaning, and textual meaning. It also distinguishes between speech and writing and discusses genre-based grammar and how genres are social processes that convey social power through specifiable linguistic characteristics.