Preposition:
* Location: Inside or within something.
* *The cat is in the box.*
* *We're in the library.*
* Time: During a period of time.
* *I'll be back in an hour.*
* *It happened in the summer.*
* State or condition:
* *I'm in trouble.*
* *He's in love.*
* Direction: Toward a place or position.
* *He went in the house.*
* *Look in the mirror.*
Adverb:
* Movement or direction: Into or towards a place.
* *Come in!*
* *He went in and closed the door.*
* Emphasis: Used to emphasize a particular word or phrase.
* *It was in fact a very difficult task.*
Other uses:
* As part of certain expressions:
* *In order to...*
* *In case of...*
* *In fact...*
* *In the meantime...*
Examples of "in" in different sentences:
* The dog is in the garden. (Location)
* I'll be home in an hour. (Time)
* He's in love with her. (State)
* I'm in a hurry. (State)
* Come in and sit down. (Movement)
* He went in and closed the door. (Movement)
* In fact, I think it's a good idea. (Emphasis)
The specific meaning of "in" will become clear based on the context of the sentence.