This document provides information about phonology. It defines phonology as the study of the distinctive sound units of a language called phonemes, and the patterns of sounds in a language. Phonology is significant for producing and recognizing sound patterns in English. It is related to phonetics, which studies sound variations, while phonology focuses on sound patterns. Phonetics has three areas - articulatory phonetics examines sound production, acoustic phonetics sound transmission, and auditory phonetics sound perception. Articulatory phonetics further describes the vocal tract, articulators like the tongue, teeth and lips that produce sounds.