Which do you use: “a” vs “an”

Judging from all of the blogs that I read as well as emails and memos at work, there is a lot of confusion when it comes to using “a”and “an.”

When I was in school I learned that the usage rule for “a” versus “an” is as follows:

• for words that start with consonants, use “a”
• for words that start with a vowel, use “an”

And generally I find this to be a god rule of thumb if you are unclear on usage.

However, while looking through some posts on Daily Writing Tips I came across some additional info, which can be found here.