2. Indefinite Article: a, an

Indefinite article 'a'

The indefinite articles a and an are used before a singular countable noun which is unspecified , that is a noun that does not refer to a specific person, animal or thing and has not been mentioned before .

The indefinite articles are not used before a plural noun or an uncountable noun .

A is used before a word that begins with a consonant.
An is used before a word that begins with a vowel, or a word that begins with a consonant but has vowel sound (e.g. hour, honour, etc)

When 'a' is used before a noun, it does not refer to that one specific noun ; it uses this noun as representing all the others .

Examples:

Example 1 : A house in that new housing estate has at least three bedrooms.
(The article a does not point out a specific house but all houses in that housing estate.)

Examples 2 : I want to buy a table.
( The use of a here indicates no special preference for a type of table or a specific table in mind to buy. )

We use a :

Examples:

when we mention something for the first time:

I saw a fairy .
Last night, I heard a scream.

to mean one single person or thing :

A stranger approached me for some money.
She has a big mole on her left cheek.

and one interchangeably:

I lost a hundred / one hundred dollars in the game.
He keeps a dozen / one dozen green snakes as pets.

before a word which begins with a consonant:

There is a policeman asking for you.
It’s a video of a mongoose fighting a snake .

before a word with a long sound of u:

a university , a uniform , a useful � book, a European , a unique design.
It would be a unique opportunity to travel in space.

before the word one because one sounds as if it begins with a W ( wun ):

a one-way street, a one-eyed � monster, a one-year course, a one-week holiday.
I have a one-way ticket to travel from one place to another in the city.

The indefinite article a also means one . We can use a or one as follows:

Examples:

We use a :

to express a degree, number or amount of something :

We’re getting a bit bored with nothing to do.
A little training is all that is required to do the work.

to show that someone or something belongs to a class of people or things:

She is a doctor . (A profession)
He is a Belarusian . (A native or national)

with a partitive before an uncountable noun :

There was a layer of fine dust on the bookshelf.
They usually have a pint of beer at lunchtime.

with illnesses or conditions :

a backache , a cold , a cough , a fever , a headache , a sore throat , a stomach ache , a toothache , etc.

to express a degree, number or amount of something :

She caught a cold while camping.
He developed a headache from staying up late for successive nights.

before abbreviations:

A BA (Bachelor of Arts), a PhD (Doctor of Philosophy)

Sometimes, it is better to use a instead of one .

Examples:

She wiped up the vomit with a mop .
Better than : She wiped up the vomit with one mop .

He had a bath before he went to bed.
Better than : He had one bath before he went to bed.

We can use a in front of a proper noun when referring to someone, or when the proper noun is used as an adjective.

Examples:

A Mr Brown called to ask when you are going to give back the borrowed money.
There was a Mr Carter who went from house to house soliciting donations for a charity.
I still remember it was on a December morning when you drove through the fog into a tree.
We agreed to meet again on a Saturday afternoon .

Indefinite article a is also used before a word that begins with a vowel but with a consonant sound ( a eulogy, a European country , a unanimous verdict , a uniform , a union , a unique opportunity , a universal truth , a university student , a used car , a useful tool, a useless attempt ).

Examples:

This is a U . �
‘Pass away’ is a euphemism for ‘die’. �
She no longer sports a unisex haircut . �
I couldn’t make a U-turn as I was driving on a motorway. �
A one-minute silence was observed at the site where the victims were found.

Indefinite article 'an'

The indefinite article an is used before a vowel sound ( an apple , an empty can , an inside job ) and an unspecified count noun, that is a noun that has not been mentioned before. Do not use ' an ,' before a plural noun or an uncountable noun, but only before a singular countable noun. The article , an , does not refer to a specific person or thing.,

We use an :

Examples:

before a noun which begins with a vowel:

They say an apple a day keeps the doctor away.
He has an oval-shaped burn scar on his arm.
That must be an oak tree , which is bigger than all the other trees around here.

before a singular noun (person or thing) to mean only one in quantity.

There is an egg in the nest.
She’s an only child .
An ostrich has only two toes on each foot.

before a noun that is representative of a group, species, etc.

It is an opal . (A precious stone)
He is an optician . (A profession)
She’s an Armenian . (A native or national)

before a word that begins with a consonant but with a vowel sound, especially the h consonant. Examples include an heir , an honest person , an honour , an honorable fellow , an hourly bus service . �

In an hour’s time , the party will be in full swing.
Each of them received an honour for their services in the rescue mission. �
I can't read your writing. Is this an h or what?

before abbreviations, some of which begin with a consonant.

I had an X-ray on my lungs. �
I saw an UFO hovering above my kitchen.
The response was quick to an SOS sent by a ship.
You must fix an L-plate not only to the back but also to the front of your car.
His father has an MSc (Master of Science) in Chemistry, and his mother has an MA (Master of Arts) in English literature.
He always wanted to be an MP but was not elected for the past twelve years.

Words beginning with u and h:

Using a and an with words beginning with u .

A and an are used before words beginning with u : a is used if the u is a consonant sound; an is used if the u has a vowel sound.

Examples:

He applied to a university to study palmistry.
Mom has a unique talent for ghost storytelling.
He had an uncle who was a great disco dancer.
She wore a raincoat and carried an umbrella.
You really believe an ugly witch has magic powers?
The scientists discovered an unusual insect that flew without wings. �

Using a and an with words beginning with h

A and an are used before words beginning with h : a is used if the h is pronounced; an is used if the h is not pronounced.

Examples:

We met at a hotel.
We argued the whole night over where to have a holiday this year.
After an hour, she recovered enough to speak on stage. .
He claimed he's an honest politician. �