A and an | when to use them

Do you get confused about when to use a and an?

If the first sound of the following word is a vowel sound (whether or not the letter is a vowel), use an.

an elephant, an hour, an honour, an urn

If the first sound of the following word is a consonant sound (whether or not the letter is a consonant), use a.

a helicopter, a hotel, a union

Using this rule, use an with acronyms such as MRI and STD. (MRI stands for magnetic resonance imaging and STD for sexually transmitted disease.)

an HIV patient (human immunodeficiency virus)

A and an are known as determiners. They are also called indefinite articles. The, which is also a determiner, is called the definite article.

Learn more

Improve your grammar with Online Writing Training’s online Grammar, Punctuation and Usage course.

Or Grammar Basics: For non-native English speakers.

Subscribe to my monthly e-newsletter to receive writing and grammar tips.