The indefinite articles a and an both mean the same thing. The definite article the refers to a particular thing (“Give me the ring! The wedding ring!”) while a and an refer to any item of a certain type (“Please hand me a nail, any nail.”) But when do you use a and when do you use an? You were probably taught in school that, preceding a vowel (“an apple”), you use an. Preceding a consonant, you use a.
Ah, but that isn’t quite true. You don’t only use an before any word that begins with a vowel. That would be too easy. You also use it before any word that sounds like it begins with a vowel! That’s why “an hour” is correct, not “a hour.” Even though h is a consonant, in hour, it’s silent.
So, should a Cockney flower vendor say, “They’re going to have an ‘urricane in Aruba” (not “a ‘urricane”) simply because, the way she says it, hurricane starts with a vowel sound? Maybe so. But even better, maybe she could learn how to pronounce the h in hurricane like the high-class ladies do. Hmm, that sounds like a great premise for a hit Broadway musical.
Editor’s note: You can read about this topic on the article “Using ‘a’ and ‘an’ Before Words.”