Someone or something that is in something else is enclosed by it or surrounded by it. If you put something in a container, you move it so that it is enclosed by the container.
e.g. He was in his car.
e.g. ...clothes hanging in the wardrobe...
If something happens in a place, it happens there.
e.g. We spent a few days in a hotel...
e.g. He had intended to take a holiday in America...
If you are in, you are present at your home or place of work.
e.g. My flatmate was in at the time...
e.g. He has had to be in every day.
When someone comes in, they enter a room or building.
e.g. She looked up anxiously as he came in...
e.g. They shook hands and went in.
If a train, boat, or plane has come in or is in, it has arrived at a station, port, or airport.
e.g. Wed be watching every plane coming in from Melbourne...
e.g. Look. The trains in. Well have to run for it now.
When the sea or tide comes in, the sea moves towards the shore rather than away from it.
e.g. She thought of the tide rushing in, covering the wet sand...
e.g. If the tide was in they went swimming.
Something that is in a window, especially a shop window, is just behind the window so that you can see it from outside.
e.g. The light in the window went out...
e.g. There was a camera for sale in the window.
If something happens in a particular year, month, or other period of time, it happens during that time.
e.g. ...that early spring day in April 1949...
e.g. Export orders improved in the last month...
If something happens in a particular situation, it happens while that situation is going on.
e.g. His father had been badly wounded in the last war.
e.g. ...issues you struggle with in your daily life.
If you do something in a particular period of time, that is how long it takes you to do it.
e.g. He walked two hundred and sixty miles in eight days.
If something will happen in a particular length of time, it will happen after that length of time.
e.g. Ill have some breakfast ready in a few minutes...
e.g. Theyll be back in six months.
You use in to indicate roughly how old someone is. For example, if someone is in their fifties, they are between 50 and 59 years old.
e.g. ...young people in their twenties.
e.g. ...Molly, a tall woman in her early sixties.
If you say that something is in, or is the in thing, you mean it is fashionable or popular.
e.g. A few years ago jogging was the in thing...
e.g. It is the in place to go for a quick drink after work.
You use in with a present participle to indicate that when you do something, something else happens as a result.
e.g. In working with others, you find out more about yourself.
If you say that someone is in for a shock or a surprise, you mean that they are going to experience it.
e.g. You might be in for a shock at the sheer hard work involved...
e.g. When you venture outside, you are in for a surprise.
If someone has it in for you, they dislike you and try to cause problems for you.
e.g. The other kids had it in for me.
If you are in on something, you are involved in it or know about it.
e.g. I dont know. I wasnt in on that particular argument...
e.g. Im going to let you in on a little secret.
If you are in with a person or group, they like you and accept you, and are likely to help you.
You use in that to introduce an explanation of a statement you have just made.
e.g. Im lucky in that Ive got four sisters.