Most students know that we use the article “an” with a noun that starts with a vowel (A, E, I, O, U):
An apple
And that we use “a” with a noun that begins with a consonant:
A banana
However, this is actually not completely accurate. The real rules are:
“An” goes before vowel sounds
“A” goes before consonant sounds
That is why we have:
An hour (the first sound is “o” not “h”
or
A University (the first sound is “y” not “u”
