Part 1 — A and An: Sound Rules & Uses

Basic rule

Use a or an before a singular countable noun when it means one non-specific member of a group.

I saw a bird.

She bought an umbrella.

Do not use a/an with a plural noun or an uncountable noun.

a books ❌

an information ❌

books ✅

some information ✅

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A before a consonant sound

a boy

a car

a teacher

a useful idea

The spelling is not the final test. The first sound is what matters.

“U” with a /y/ sound

a university

a uniform

a union

a useful book

a unique opportunity

These begin with a “you” sound, which is a consonant sound.

“Eu” with a /y/ sound

a European

a eulogy

a euphemism

“One” with a /w/ sound

a one-eyed man

a one-rupee coin

a one-time payment

One begins with a /w/ sound.

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An before a vowel sound

an apple

an engineer

an orange

an umbrella

Silent h

an hour

an honest person

an honour

an heir

The first spoken sound is a vowel.

Pronounced h

a house

a hotel

a historical event

a hero

In ordinary modern pronunciation, the h is spoken.

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Abbreviations and initials

Choose the article according to how the first letter is pronounced.

Letters beginning with vowel sounds

The letters A, E, F, H, I, L, M, N, O, R, S, X begin with vowel sounds when spoken.

an MBA graduate

an NGO worker

an FIR

an SMS

an LLB degree

an X-ray

an HEC official

an R&D department

Letters beginning with consonant sounds

a UN mission

a USB drive

a UFO

a BBC reporter

a PhD student

UN begins “you-en,” and USB begins “you-es-bee.”

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Acronyms pronounced as words

If the abbreviation is pronounced as a word, listen to that word.

a NATO official

“NATO” begins with an /n/ consonant sound.

a NASA scientist

an AIDS patient

“AIDS” begins with a vowel sound.

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First mention and one of many

Use a/an when the listener does not yet know which person or thing is meant.

I saw a car outside.

She spoke to an officer.

Later, use the:

The car was damaged.

The officer recorded her statement.

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Profession, religion and classification

Use a/an to state what someone is.

She is a doctor.

He is an engineer.

She is a Muslim.

It is an insect.

Do not omit the article before a singular countable profession.

She is doctor. ❌

She is a doctor. ✅

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Meaning “one”

I need a pen.

He bought a kilogram of rice.

She waited for an hour.

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Rate, frequency and price

Use a/an in expressions meaning “per.”

twice a day

sixty kilometres an hour

five hundred rupees a kilogram

three times a week

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Exclamations

What + a/an + singular countable noun

What a beautiful day!

What an excellent idea!

Do not use a/an before an uncountable or plural noun in the same way:

What beautiful weather!

What lovely flowers!

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A certain or unknown person

A Mr Khan called you.

This means a person called Mr Khan whom the speaker does not know well.

Compare:

Mr Khan called you.

This identifies the known person directly.

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A/an with descriptive adjective

The article comes before the adjective, but the noun still determines whether the phrase is singular countable.

a beautiful house

an interesting book

Choose a/an by the first sound after the article:

an unusual event

a useful event

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Common errors

Error 1

an university ❌

a university ✅

Error 2

a hour ❌

an hour ✅

Error 3

an European country ❌

a European country ✅

Error 4

a MBA graduate ❌

an MBA graduate ✅

Error 5

an one-eyed man ❌

a one-eyed man ✅

Error 6

an hotel ❌ in standard modern pronunciation

a hotel ✅

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Quick sound table