Definite and indefinite articles

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1. Definite and indefinite articles

The definite (the) and indefinite articles (a/an) are those determiners that indicate the identity of the noun they accompany, that is, they tell us if the element being talked about is something specific or non-specific.
IMG UNIT 13-1
The food is excellent.
IMG UNIT 13-2
Do you have a dress for me?

2. When do we use the definite articles?

We use the definite article the when we refer to a specific element and/or it is known by the speaker. In all cases the same article is used, regardless of gender or number.

IMG UNIT 13-3
Can you close the door?
IMG UNIT 13-4
The cats are sleeping on my bed.

The definite article the has a different pronunciation depending on the word it precedes:

Definite article Use Pronunciation Examples
THE When the word begins with a vowel [ði] The apple
When the word begins with a consonant [ðə] The dog

We also use the definite article the in the following cases:

Uses Examples Sentences
With nouns that refer to unique things, that is to say, that there is only one. The sun, the moon, the sky... The sun rose at 6:15 this morning.
With things we know there's only one in a particular place or time. The car (we only have one) the church (there's only one in town)... Can I use the car next Saturday?
With singular countable nouns when we refer to them in general. The whale... The whale is a marine mammal.
With musical instruments. The violin... I used to play the violin when I was little.
With adjectives to refer to a group of people. The rich, the French... The rich always get richer.
With oceans, seas and rivers. The Atlantic Ocean, The Nile The Titanic sank in the Atlantic Ocean.
With mountain ranges. The Alps, The Pyrenees... Which is the highest mountain in the Alps?
With groups of islands and deserts. The Bahamas, The Sahara... I spent my holidays in the Bahamas.
With museums, cinemas or theatres. The British Museum, The Phoenix Thousands of tourists visit The British Museum every year.
With some countries. The Czech Republic, The United States... I have some relatives in The Czech Republic.
With famous buildings and monuments. The Taj Mahal, The London Eye... The Taj Mahal is one of the seven wonders of the world.
In front of a superlative. The best, the biggest... He is the best player at the moment.

There are cases where the definite article the is omitted in English:

Uses Examples Sentences
With plural countable nouns to talk about something in general. Computers, butterflies... The Computers are constantly evolving.
With uncountable nouns to talk about something in general. Life, nature, space... The Life is short so live it to the full.
With continents, countries and cities. Africa, France, London... The Africa is an amazing continent.
Streets, stations or airports. Oxford Street, Penn Station... My grandma lives in the Oxford Street.
Lakes, mountains and islands. Lake Victoria, Kilimanjaro, Malta... We've booked a hotel by the Lake Victoria.
With people's names. John, Mary... The John has finally asked the Mary out.
Time, days and months. 3:15, Monday, June We met on the Monday at the 3:15.

3. When do we use the indefinite articles?

We use the indefinite article a or an when we want to refer to an undetermined element or one that is unknown to the speaker.

IMG UNIT 13-5
Do you have an umbrella?
IMG UNIT 13-6
There is a frog in the garden.

Depending on the word they precede, a or an will be used:

Indefinite articles Use Pronunciation Examples
A When the word begins with a consonant [ə] A cake
When the H at the beginning of the word is pronounced [ə] A hospital
When the word begins with E or U with a consonant sound [ə] A university
AN When the word begins with a vowel [ən] An ice-cream
When the H at the beginning of a word is silent [ən] An hour
Plural countable nouns and uncountable nouns can’t be preceded by an indefinite article.
I need some sugar.
I need a sugar.
I want some cakes for my birthday.
I want a cakes for my birthday.

We also use the indefinite article a / an in the following cases:

Uses Examples Sentences
Before jobs. A nurse, an accountant... My mum is a nurse at the hospital.
To replace the number one. An apple, a hundred... Can I have an (one) apple, please?
Before a singular countable noun that is an example of a kind of things. A lion, a book A baby lion is born blind.
Expressions of price, speed... A kilo, an hour... The oranges cost 2 euros a kilo.

4. Differences between a / an and the

  • We will use the indeterminate article a / an when we refer to something in general, whereas we will use the determinate article the when we already know what we are referring to.
    IMG UNIT 13-7
    I need a jacket.
    In this example we use the article a because we are referring to any jacket.
    IMG UNIT 13-8
    I need the jacket.
    In this example we use the article the because they both know what jacket they are talking about.
  • We will use the indeterminate article a / an when we refer to something for the first time, whereas we will use the determinate article the when what we are referring to has already been mentioned.
    IMG UNIT 13-10
    He has adopted a dog. The dog is docile.
    IMG UNIT 13-11
    She's wearing a short dress. The dress is made of silk.
    In both examples, when we first mention the thing we want to refer to (dog / dress) we use the indefinite article a, while when we mention them for the second time we use the definite article the.

Remember!

The definite (the) and indefinite articles (a/an) are those determiners that specify the identity of the noun they accompany, that is, they tell us if the element being talked about is something specific or non-specific.
  Use Examples
INDEFINITE ARTICLE
A / AN
Before a job. She is an astronaut.
To replace number one. I drink a coffee every morning.
Before a singular countable noun when it's used to act as an example of a kind of things. A book is always a good present.
Expressions of price, speed... This car can run at 250 miles an hour.
DEFINITE ARTICLE
THE
With nouns that refer to unique things, that is to say, that there is only one. The moon is so beautiful tonight.
With things we know there's only one in a particular place or time. The church is being restored.
With singular countable nouns when we refer to them in general. The wheel is one of man's most important inventions.
With musical instruments. When did you start playing the piano?
With adjectives referring to a group of people. The Finns have a very good education system.
With oceans, seas and rivers. We took a cruise on the Nile.
With mountain ranges. We are flying over the Pyrenees.
With groups of islands and deserts. The Gobi Desert is the largest desert in Asia.
With museums, cinemas or theatres. There's a very interesting exhibition at the Guggenheim museum.
With some countries. I have some relatives in The Netherlands.
With famous buildings and monuments. There's always a long queue to go up the Eiffel Tower.
Before a superlative. I booked the cheapest hotel.
OMISSION OF THE With plural countable nouns to talk about something in general. I hate spiders.
With uncountable nouns to talk about something in general. Music connects people.
With continents, countries and cities. Have you ever been to Budapest?
Streets, stations or airports. I live on Carnaby Street.
Lakes, mountains and islands. We're planning to climb Kilimanjaro.
With people's names. Have you seen Peter lately?
Time, days and months. I usually go to bed at 23:00.