The definite article the is the most frequent word in English.
We use the definite article in front of a noun when we believe the hearer/reader knows exactly what we are referring to.
• because there is only one:
The Pope is visiting Russia.
The moon is very bright tonight.
The Shah of Iran was deposed in 1979.
This is why we use the definite article with a superlative adjective:
He is the tallest boy in the class.
It is the oldest building in the town.
• because there is only one in that place or in those surroundings:
We live in a small village next to the church. = (the church in our village)
Dad, can I borrow the car? = (the car that belongs to our family)
When we stayed at my grandmother’s house we went to the beach every day. = (the beach near my grandmother’s house)
Look at the boy in the blue shirt over there. = (the boy I am pointing at)
• because we have already mentioned it:
A woman who fell 10 metres from High Peak was lifted to safety by a helicopter. The woman fell while climbing.
The rescue is the latest in a series of incidents on High Peak. In January last year two men walking on the peak were killed in a fall.
We also use the definite article:
• to say something about all the things referred to by a noun:
The wolf is not really a dangerous animal (= Wolves are not really dangerous animals)
The kangaroo is found only in Australia (= Kangaroos are found only in Australia)
The heart pumps blood around the body. (= Hearts pump blood around bodies)
We use the definite article in this way to talk about musical instruments:
Joe plays the piano really well.(= Joe can play any piano)
She is learning the guitar.(= She is learning to play any guitar)
• to refer to a system or service:
How long does it take on the train?
I heard it on the radio.
You should tell the police.
• With adjectives like rich, poor, elderly, unemployed to talk about groups of people:
Life can be very hard for the poor.
I think the rich should pay more taxes.
She works for a group to help the disabled.
