Indefinite Articles: A and An

Indefinite articles are used when we are referring to an unspecified thing or quantity. We use them when we don’t know (or don’t care) which thing we’re talking about.

There once was a sheep.

Since I don’t know which sheep it was—that is, I don’t know its name, where it’s from, or anything about it—I can’t say the sheep.

How to Use the Indefinite Articles A vs. An

The two indefinite articles in English are a and an. The indefinite article an is used to make pronunciation easier when reading a text aloud. The general rule is to use a when the indefinite article precedes a word beginning with a consonant sound and an when it precedes a word starting with a vowel sound.

1 Use a when the indefinite article comes before a word beginning with a consonant sound: a toy a book a house

2 Use an when the indefinite article comes before a word beginning with a vowel sound:

an operation an idea an apple

Exceptions

It’s important to note that not all nouns that begin with a consonant begin with the consonant sound. Always trust the sound, not the letter when applying the a vs. an rule. Remember, it’s about pronunciation. Consider the examples below:

a hourglass
an hourglass

a honor
an honor

Likewise, there are some nouns beginning with a consonant that makes a vowel sound. In these cases, the indefinite article a should be used:

an university
a university

an one-eyed pirate
a one-eyed pirate

Using A vs. An with Acronyms

These same rules apply to acronyms:

A Society of Writers member was quoted in the article.
A S.O.W. member was quoted in the article.
An S.O.W. member was quoted in the article.

Because S sounds like it begins with a vowel (ess), an should be used in front of it.

Weekly Grammar Tips
Weekly Grammar Tips
Want more good reads?

Get the best stories delivered to you each week.

Your writing, at its best
Why not make your writing mistake-free across the web?
Get Grammarly It’s free
Blog Updates
Sign up for our weekly newsletter and never miss a story.
Want more good reads?

Get the best stories delivered to you each week.

Embed Code

Copy code below to embed this post to your site.