Grammar (from Ancient Greek γραμματική grammatikḗ) is a system of rules which governs the production and use of utterances in a given language. These rules apply to sound as well as meaning, and include componential subsets of rules, such as those pertaining to phonology (the organisation of phonetic sound systems), morphology (the formation and composition of words), and syntax (the formation and composition of phrases and sentences). Modern frameworks that deal with the principles of grammar include structural and functional linguistics, and generative linguistics.