This document provides an overview of phonetics and phonology. It defines phonemes as the smallest units of sound that distinguish meaning, and allophones as contextual variants of phonemes. It describes broad and narrow phonetic transcription. It then outlines 20 phonological rules describing allophonic variations in English pronunciation governed by phonetic context and position, such as voicing, aspiration, nasalization, syllabification. It concludes with an outline of the topics covered and an example exercise transcribing words.