Definite and indefinite articles: the, a, an

The definite article the as a determiner can be used before singular or plural nouns such as people or things, and before countable and uncountable nouns.

We use the determiner the:

to refer to people or things which we know because they have already been mentioned.

  • There is a man doing magic at the marketplace. I know the man; he is my uncle.
  • I know there are bats in that cave. I have been to the cave and seen the bats.

to refer to a person or thing when there is only one.

  • He is the ex-husband of my friend’s sister.
  • The flood occurred only in the east coast of the country.

before superlatives, words such as firstonly, etc.

  • Peacocks have themost beautiful feathers.
  • Thefirst runner to cross the line will be declared the winner.
  • This duckling is the only pet I have.

before adjectives so that the adjectives become nouns. 

  • Sometimes I hate myself for dreaming the impossible.
  • They buried the dead as soon as they could.

before a singular noun that is representative of a group of similar people or things.

  • A large and flightless bird, the dodo is now extinct.
  • The satellite has many uses, the most important of which is the transmission of information.

before proper nouns.

  • The Robinsons are the latest members of the ghost-hunting club.
  • The Niagara Falls is the largest waterfall in the world.

We use the determiners a/an:

to refer to someone or things that we know nothing about as they have not been mentioned before, or they are not particular persons or things.

  • She brought home puppy.
  • They saw man attempting to commit burglary at house near by.
  • There was anexplosion in a nearby factory.

before an uncountable noun.

  • The husband and wife share a liking for raw fish.
  • He has an unusually bad temper.

before an action noun.

  • She had a quick glance at me, and then looked away.
  • She always has abath that lasts at least an hour.

before a quantity.

  • He uttered a few foreign words before he passed away.
  • She never does a bit of exercise to reduce her enormous body weight.

before a proper noun such as a person’s name.

  • A Mr. Wilson called while you were away.
  • Is there a Patterson here?