Vowels: a, e, I, o, u and sometimes y are vowels
We use AN before a word if it begins with a vowel.
Example: I can eat an apple.
A vowel is a speech sound made by the vocal cords. It is also a type of letter in the alphabet.
The letters of the English alphabet are either vowels or consonants or both. A vowel sound comes from the lungs, through the vocal cords, and is not blocked, so there is no friction. All English words have vowels.
These letters are vowels in English: A, E, I, O, U, and sometimes Y
The letter Y can be a vowel (as in the words "cry", "sky", "fly" or "why"), or it can be a consonant (as in "yellow", "yacht", "yam" or "yesterday").
These five or six letters stand for about 20 vowel sounds in most English accents. This important fact helps to explain why pronunciation can be difficult for both native speakers and learners of English.
The rest of the letters of the alphabet are consonants: