‘a’ and ‘an’
You usually use a and an when it is not clear or important which specific thing or person you are referring to. You only use a and an with singular countable nouns. When you are talking about a specific person or thing, you usually use the.
She decided to buy a car.
He parked the car in front of the bakery. Determiners
You can describe someone or something using a or an with an adjective and a noun, or with a noun followed by more information.
His brother was a sensitive child.
The information was contained in an article on biology.
Don't omit a or an in front of a noun when the noun refers to someone's profession or job. For example, you say ‘He is an architect’. Don't say ‘He is architect’.
She became a lawyer.
‘a’ or ‘an’?
You use a in front of words beginning with consonant sounds and an in front of words beginning with vowel sounds.
Then I saw a tall woman standing by the window.
We live in an old house.
You use an in front of words beginning with ‘h’ when the ‘h’ is not pronounced. For example, you say ‘an honest man’. Don't say ‘a honest man’.
The meeting lasted an hour.
An is used in front of the following words beginning with ‘h’:
You use a in front of words beginning with ‘u’ when the ‘u’ is pronounced /juː/ (like ‘you’). For example, you say ‘a unique occasion’. Don't say ‘an unique occasion’.
He was a university professor.
She became a union member.
is used in front of the following words:
You use an in front of an abbreviation when the letters are pronounced separately and the first letter begins with a vowel sound.
Before she became an MP, she was a social worker.
He drives an SUV.
‘a’ meaning ‘one’
A and an are used to mean ‘one’ in front of some numbers and units of measurement. Numbers and fractions