- He's gone to the shops.
* Here the listener knows which shops I mean
You use "the" when you know that the listener knows or can work out what particular person/thing you are talking about.
- The apple you ate was rotten.
- Did you lock the car?
You should also use "the" when you have already mentioned the thing you are talking about.
- She's got two children; a girl and a boy. The girl's eight and the boy's fourteen.
- An elephant and a mouse fell in love. The mouse loved the elephant's long trunk, andthe elephant loved the mouse's tiny nose.
We use the to talk about geographical points on the globe.
- the North Pole, the equator.
We use the to talk about rivers, oceans and seas.
- the Nile, the Pacific, the English channel
We also use the before certain nouns when we know there is only one of a particular thing.
- the rain, the sun, the wind, the world, the earth, the White House etc..
It can be used to refer to a group.
- the Japanese, the old
- The car has changed our way of living.
Before superlatives and ordinal numbers.
- the highest building, the first page, the last chapter.
In sentences or clauses where we define or identify a particular person or object.
- The man who wrote this book is famous.
- My house is the one with a blue door.
With decades, or groups of years.
- He grew up in the seventies