the—Definite Article

A. Used when we (speaker and listener) know “which one”

1. We have mentioned it before.

• He has a mother. The mother is sick.

2. We say which one we mean.

• The man with the yellow hat is George's friend.

3. It is clear from the situation which one we mean.

• Everybody went to the picnic.
• He spoke to the boss about getting a raise. (You know which one - my boss.)
• Please turn off the light when you're done. (You know that the light in the room is the one I'm talking about.)

B. There is only one around.

• The Black Death devastated Europe in the 14th century.
• People say that the moon is made of green cheese.

C. It concerns the physical environment.

1. The city, the country, the weather, the sea, the future, etc.

• Listen to the falling rain.
• Do you want to go camping in the mountains on your vacation, or would you rather rent a cottage by the seashore?
• Some people would rather live in the country instead of the city.

2. Used with superlatives—usually only one best, biggest, etc., so we know which one.

• That's the biggest park in our town.

3. Also used with first, next, last, same, only

• It was a coincidence that we got the same score on our tests.
• That's the last straw - I will never shop there again.

4. “the” = “the well-known”

• The President will give his State of the Union address tonight.
• Did you ever see Yo-Yo Ma, the cellist?

When “the” is NOT used:

A. Possessives and demonstratives.

• My father is an engineer. (Not The my father is an engineer.)
• Give me that book when you're done. (Not Give me that the book when you're done.)

B. Proper names.

• They went to Canada on their vacation. (Not They went to the Canada on their vacation.)

C. Things in general.

• Cats are popular pets. (Not The cats are popular pets.)