Indefinite article

For example:

• A white house on a green hill.
• A cat ate the sardine
  * We are not specifying which cat ate the sardine, it could have been any cat.

Notes:

It is normal to use the indefinite article when we mention someone or something for the first time in our conversation or text.

For example:

• I've finally got a good job.
• We bought a new computer and it was cheap.
• Would you like a drink?

"A" and "an" are also used to refer to a particular member of a group or class.

For example:

• She is an English teacher.
• He wants to be a dancer.
• John is an Englishman.
• Sherlock Holmes was playing a violin when the visitor arrived.
• I was born on a Thursday.

We also use the indefinite article to talk about price / weight, speed.

For example:

• This car does 240 km an hour.
• It is 10 euros a kilo.

Certain numbers in English require the presence of an indefinite article.

For example:

• A hundred, a thousand, a million, etc...

With singular nouns, after the words "what" and "such"

For example:

• What a day!
• What a shame!
• She's such a beautiful girl.

Meaning "one", referring to a single object or person

For example:

• I'd like an orange and two lemons please.
• The burglar took a diamond necklace and a valuable painting.

The choice between "a" and "an"
Depends on the initial sound of the adjective that immediately follows the article:

Use "a" with nouns starting with a consonant. On the other hand, we use "an" before nouns starting with a vowel.

For example:

• an umbrella
• a table
• an elephant
• a book

NOTE: If the next word begins with a consonant sound when we say it then we use a. If the next word begins with a vowel sound when we say it then we use an.

For example:

• We say "university" with a "y" sound at the beginning as though it were spelt "youniversity".
  => a university
• We say "hour" with a silent h as though it were spelt "our".
  => an hour

Determiner
Definite Article