1. Used for belonging to, relating to, or connected with. Example :
a. The highlight of the show is at the end.
b. I always dreamed of being rich and famous.

2. Used to indicate reference. Example :
a. I got married in the summer of 2000.
b. This is a picture of my family.

3. Used to indicate an amount or number. Example :
a. I drank three cups of milk.
b. A large number of people gathered to protest.