They do it for fun. Sometimes one person will jump. Sometimes a group of people will jump at the same time. Parachutes are also used by the military. Soldiers jump with parachutes into battle.
Equipment is dropped to soldiers by parachutes.
The parachute is put into a pack when not being used. The rip cord opens the pack and the parachute comes out. Air fills the parachute as it opens. There is a small hole in the top of the parachute. Air goes through the hole.