When to use ’a’ versus ’an’
’A’ or ’an’? Well, normally the rules are clear, but there are exceptions if the word is pronounced differently than it looks.
If a word begins with a consonant sound, you must use ’a’. If it begins with a vowel sound, use ’an’. In other words, using ’a’ and ’an’ does not depend on the spelling of the word it comes before; it depends on the pronunciation of the word. For example: