Phonology is the branch of linguistics that studies the sounds of language and how they function within a particular language system. This includes the study of phonemes, which are the individual sound units that distinguish one word from another in a given language, as well as phonological rules and patterns that govern the organization and use of these sounds. Phonologists also investigate how sounds change and vary in different contexts, dialects, and languages, as well as how they are produced and perceived by speakers. Overall, phonology plays a crucial role in helping linguists understand the structure and function of language sound systems.