How to use 3 confusing words a / an / one

How to use 3 confusing words a / an / one

a / an / one
Use one when the number is important; when you want to emphasize that it is only one (and not two or three or more):
One of these eggs is rotten, but the others are OK.

• I wanted to buy three Books, but I didn’t have enough money, so I bought only one.

In all other cases, when the fact of being “one” is not important, use a / an:

• I had an omelet for breakfast.

• I bought a new Book yesterday.

What about the difference between a and an? We use an before words beginning with a vowel sound, and a before all other words:

• an orange / a pineapple

• an avocado / a football

• an apricot / a coconut

• an omelet / a steak

• an umbrella / a uniform (because “uniform” is pronounced yuniform)

• an hour / a hat (we use an with hour because the H in hour is silent, but the H in hat is not)