Originally Posted by
s25843
The grammar rules I was taught many moons ago, was to use AN when the first letter of the next word is a vowel.... An apple, An Idiot, An Airplane...
Well, that can't be universal because we do not say "An European." And some people do put AN when the next word starts with a consonant, "An Historic occasion."
The real rule is that if the next word begins with a vowel
sound, use AN. If it begins with a consonant sound, use A.