We use the Indefinite Article – a or an – when we talk about:

We never use the indefinite article with non-countable nouns:

* I swam in a clean water and ate a pasta.

* an asterisk denotes ungrammatical English

Before a Vowel

A or An? The general rule is that we use a before a consonant and an before a vowel:

a bowl
a car
a dog

but…

an ant
an elephant
an insect
an orange
an urn

But, what is important here is not the way a word is written, but the way it sounds. We choose a or an depending on the sound at the beginning of the word and whether it is a vowel sound or a consonant sound.

For example, take the word uniform. Although it begins with a vowel – u – when we write it, when we say it the first sound is /y/ which is a consonant:

uniform is pronounced /ˈjuːnɪfɔːm/ so we say a uniform

One word which is often confused is hotel. Some people pronounce this word as /həʊˈtɛl/ so they would write:

a hotel

But other people pronounce this word as /əʊˈtɛl/ and so they would write:

an hotel

Useful Links

Articles‏‎ in English Grammar – a general look at articles in English