This document provides an introduction to phonology, the study of sound patterns in language. It defines key phonological concepts including phonemes, phones, and allophones. Phonemes are the smallest units that distinguish meaning, while phones are actual speech sounds and allophones are variant pronunciations of the same phoneme. The document uses examples from English and other languages to illustrate these concepts and how they are identified, particularly through finding minimal pairs. It also discusses other phonological topics like phonotactics, syllables, and phonological processes.