Diphthongs are linguistic elements that fuse two adjacent vowel sounds. English has four common diphthongs. The commonly recognized diphthongs are /aʊ/ as in cow and /ɔɪ/ as in boil. Three of the long vowels are also in fact combinations of two vowel sounds, in other words diphthongs: /aɪ/ as in "I" or mine, /oʊ/ as in no, and /eɪ/ as in bay, which partly accounts for the reason they are considered "long".