1. THE DEFINITE ARTICLE (THE)
We use the:
With things we have already mentioned or when it’s clear who/what we are referring to:
Example: She bought a laptop. They told her that the laptop had a three-year guarantee.
With things which are unique:
Example: the Internet, the world, the sun

2. With the names of countries which include Republic, Kingdom, States and Emirates :
Example: The United Kingdom, The United States
With an adjective used as a noun describing a nationality:
Example: the Japanese, the French, the Germans
With the name of a whole family:
Example: the Beatles, the Mitchells
With adjectives to express groups:
Example: the rich, the poor

3. With the names of rivers, seas, oceans, canals
Example: the Danube, The Adriatic Sea, The Atlantic
With a group of mountains:
Example: the Alps, the Himalayas
With instruments:
Example: He plays the guitar.
With hotels, restaurants, cinemas, theatres...
Example: the Hilton, the Opera House, the National theatre

4. With superlatives:
Example: the best, the worst, the biggest
When the noun is followed by of:
Example: Belgrade is the capital of Serbia.
When the noun is followed by a defining relative clause:
Example: The social network we use most often is Facebook.
With common expressions
Example: at the moment, at the age of 10, in the end

5. INDEFINITE ARTICLE (a, an)
We use a, an:
(An + a,e,i,o,u)
For singular, countable nouns:
Example: a student, a pupil, an essay
For something that has not been mentioned before
Example: I’ve just heard an amazing story.
For professions
Example: She is a teacher.

6. To talk about things in general
Example: A dog is a devoted animal.
With certain words which express an amount
Example: a great deal, a lot, a little, a few
With expressions of frequency
Example: once a month, twice a week
Meaning one
Example: in an hour (one hour), a million (one)

7. We don’t use articles:
When talking in general:
Example: Business people prefer five-star hotels.
When using abstract nouns:
Example: She hates dishonesty.
With the name of a language
Example: I speak English. (but: The English language is spoken all over the world.)
With an adjective
Example: He is tall. (but: He is a tall boy)

8. With an airport or train station
Example: Gatwick Airport, Charing Cross Station
With a university
Example: Cambridge University
With a shop or bank named after people
Example: Harrod’s, McDonald’s, Barclay’s bank
With a church or cathedral
Example: St Paul’s Cathedral
With meals
Example: We always have lunch together.

9. With an illness
Example: He has cancer.
With streets or roads
Example: She loves shopping in Oxford Street.
With a mountain or continent
Example: Mount Everest, Europe
With countries and cities
Example: England, London
With lakes
Example: Lake Ontario

10. With hospitals, schools, universities, churches, prisons
With hospitals, schools, universities, churches, prisons...when we think of the purpose of the institution
Example: He is in hospital (as a patient).
He goes to the hospital (to visit a patient).
With the means of transport (a way of travelling)
Example: I always go to the seaside by car.
With the names of days, holidays, months, seasons
Example: Sunday, summer, June