How do you use an in a sentence

The number one rule is this: if a word is countable (e.g. one book, two books), you must always use an article (or my, his, etc.):

 

I read a book. √

I read book.

This is true even if there are adjectives before the noun:

He drives an old car. √

He drives old car.

Never use a or an with a word that is plural (e.g. books, trees) or uncountable (e.g. water, advice):

I asked her for advice. √

I asked her for an advice.

Note that we use a in front of words that start with a consonant sound (a horse, a carrot) and an in front of words with a vowel sound (an apple, an elephant).

The next most important thing to understand is the difference between a/an and the. Basically, we use a/an when we don’t need to say which thing we are talking about. We use the to talk about a specific thing:

I caught a train to London. (it doesn’t matter which train)

The train was late. (that particular train was late)

We often use a when we mention something for the first time, and then change to the when it is clear which thing we are talking about:

He was talking to a man. The man was laughing.

She gave him a present. The present was very expensive.

We also use the when it is obvious which thing we are talking about or when there is only one of something:

Could you shut the door, please?

I cleaned the bathroom this morning.

He travelled around the world.

The sun is hot today.

If you stick to the rules above, you will be correct in almost all cases. However, there are a few exceptions, and the following are the most useful ones to learn:

We don’t use a/an before the names of meals:

We had lunch at noon.

We don’t use a/an before words like school, prison, or college when we are talking about them in a general way:

I hope to go to college.

He spent three years in prison.

With the word ‘hospital’, there is a difference between British and American English:

My brother’s in hospital (UK) / in the hospital (US).

We use the before the names of shops or places where we go for services when they are the ones we usually go to:

Note that the rule is not whether they start with a consonant or vowel, but whether they start with a consonant or vowel sound. This can help you decide which to use in difficult cases like words beginning in ‘u’ or ‘h’.

Examples: A in a sentenceExamples: An in a sentenceHe had a dog when he was a child.

Oranges are a source of Vitamin C.

She had an aneurysm when she was a child.

Many employees of the company owned an iPhone.

A usurper to the throne was imminent.Following an SOP is a good way to ensure everything goes smoothly.

Table of contents

1. A or an before H
2. A or an before U
3. A or an before acronyms
4. Worksheet: A vs an
5. Other interesting language articles
6. Frequently asked questions

A or an before H

The rule of thumb for words beginning in ‘h’ is to consider the way the word is pronounced. Words that have a silent ‘h’ begin with a vowel sound, so they use ‘an’.

• Words where the ‘h’ sound is pronounced, such as hat, hotel, or hard, use ‘a’.
• Words where the ‘h’ is silent, such as honour, hour, or honest, use ‘an’.

Example: Words beginning in ‘h’She wore a hat to keep out the sudden chill in the air.

They bought a house in May of last year.

He was thought to be an honest person, so his lies came as a surprise.

The meeting took an hour.

A or an before U

Similarly, for words beginning in ‘u’, consider the way the word sounds.

• Words where the ‘u’ sound is pronounced like ‘you’, such as user, usual, or utilised, use ‘a’.
• Words where the ‘u’ sound is pronounced like ‘uh’, such as unusual, understanding, utter, use ‘an’.

Example: Words beginning in ‘h’The email was about an urgent matter.

They came to an understanding about the cost of the repair.

It would have been helpful to have a user manual.

The invention of scissors proved a useful one.

A or an before acronyms

The same rule applies to acronyms—say the acronym aloud to sound out whether it begins with a consonant sound or a vowel sound.

Some acronyms (like ‘NASA’) are usually pronounced as full words, others (like ‘TV’) by saying the individual letters. But remember that even the spoken form of a consonant can begin with a vowel sound (e.g., [em] for M, [aitch] for H).

• Acronyms beginning with a consonant sound use ‘a’.
• Acronyms beginning with a vowel sound use ‘an’.

Example: AcronymsA NATO [nay-toe] regiment landed amphibiously during the night.

The hospital acted swiftly to prevent a HIPAA [hip-uh] violation.

An MRI [em-arr-eye] machine uses magnets to take detailed scans of your organs.

It can be expensive to pay for an SAT [ess-ay-tee] prep course out of pocket.

Worksheet: A vs an

Test your knowledge of the difference between ‘a’ and ‘an’ with these practice sentences. Fill in either ‘a’ or ‘an’ in each sentence.

• Practice questions
• Answers and explanations

1. The trail ended at __ hut.
2. I was not __ witness to anything, I promise!
3. He accidentally ate  __ poisonous mushroom.
4. The waiter brought us __ apple pie.
5. __ HIV-positive diagnosis is typically treated with antiretroviral therapy.
6. She has been in there for __ hour already.

1. The trail ended at a hut.
   • Since ‘hut’ begins with a hard ‘h’ sound, you use ‘a’.

1. I was not a witness to anything, I promise!
   • Since ‘witness’ begins with a consonant sound, you use ‘a’.

1. He accidentally ate a poisonous mushroom.
   • Since ‘poisonous’ begins with a consonant sound, you use ‘a’.

1. The waiter brought us an apple pie.
   • Since ‘apple’ begins with a vowel sound, you use ‘an’.

1. An HIV-positive diagnosis is typically treated with antiretroviral therapy.
   • Since the ‘h’ in the acronym ‘HIV’ is pronounced as [aitch], you use ‘an’.

1. She has been in there for an hour already.
   • Since the ‘h’ in ‘hour’ is silent, you use ‘an’.

Other interesting language articles

If you want to know more about commonly confused words, definitions, and differences between US and UK spellings, make sure to check out some of our other language articles with explanations, examples, and quizzes.

Confused words

• Empathy vs sympathy
• Everyday vs every day
• Its vs it’s
• Principal vs principle
• Then vs than

Definitions

• Bear with me
• Indubitably
• Misnomer
• Protagonist
• Vice versa

US vs. UK spellings

• Canceled vs cancelled
• Dreamt vs dreamed
• Gray vs grey
• Theater vs theatre
• Toward vs towards

Frequently asked questions

Is it ‘an historic’ or ‘a historic’?

A and an are different forms of the indefinite article. Words where the ‘h’ sound is pronounced, such as hat, hotel, or hard, use ‘a’ instead of ‘an’. Since ‘historic’ begins with a hard ‘h’ sound, you use ‘a historic’ instead of ‘an historic’.

• A historic battle
• A historical fossil

Is it ‘an unique’ or ‘a unique’?

A and an are different forms of the indefinite article. Words where the ‘u’ sound is pronounced like ‘you’, such as user, usual, or utilised use ‘a’ instead of ‘an’. Since ‘unique’ begins with this ‘you’ sound, you use ‘a unique’ instead of ‘an unique’.

• A unique hair color
• A unique situation

Is it ‘an hour’ or ‘a hour’?

A and an are different forms of the indefinite article. Words where the ‘h’ is silent, such as honor or honest, use ‘an’ instead of ‘a’. Since the ‘h’ in ‘hour’ is silent, it is ‘an hour’ instead of ‘a hour’.

• An hour ago
• An hourly wage

Is it ‘an honour’ or ‘a honour’?

A and an are different forms of the indefinite article. Words where the ‘h’ is silent, such as hour or honest, use ‘an’ instead of ‘a’. Since the ‘h’ in ‘honour’ is silent, you use ‘an honour’ instead of ‘a honour’.

• It’s an honour
• An honourable person

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How do you put a or an in a sentence?

A and an are two different forms of the same word: the indefinite article a that is used before noun phrases. Use a when the noun or adjective that comes next begins with a consonant sound. Use an when the noun or adjective that comes next begins with a vowel sound.

What is the rule for using an?

The two indefinite articles in English are a and an. The indefinite article an is used to make pronunciation easier when reading a text aloud. The general rule is to use a when the indefinite article precedes a word beginning with a consonant sound and an when it precedes a word starting with a vowel sound.

What are the 10 examples of article an?

Article 'An' :.

She's having an umbrella..

She's an introvert..

He's not an extrovert..

I'm eating an apple..

She's eating an egg daily..

She's going to fly an aeroplane..

An elephant is such a huge animal..

She's not eating an orange..