Phonotactics is a branch of phonology that studies the permissible combinations of sounds (phonemes) within a language. It focuses on the rules and constraints that govern the sequencing of sounds in a language, including which sounds can occur in specific positions within a word, which sounds can cluster together, and which sounds are prohibited from occurring together. Phonotactics play a crucial role in shaping the phonological structure of a language and influences the syllable structure, stress patterns, and overall phonotactic inventory of a language. Researchers in this area analyze and describe the phonotactic patterns of different languages to better understand the underlying principles that govern sound patterns and constraints in language.