This document discusses diphthongs in English linguistics. It defines diphthongs as vowels with two target configurations represented by two vowel symbols joined together. It notes that diphthongs have a significant glide from one articulatory position to another. It then proceeds to describe the distinctive features, articulatory movements, and spelling patterns of each individual diphthong phoneme in English, distinguishing between closing diphthongs which glide from more open to close positions and centering diphthongs which glide from peripheral to more central positions.