The reasons for a door are:
- for people, animals, and objects to go through; some doors are for emergencies only (emergency exit)
- to keep cold or hot air outside (or inside, such as the door on a refrigerator)
- so that people cannot see or hear what happens on the other side (privacy and stopping noise)
- so that people do not fall out of the car or other vehicle
- so a person can decide who to let in—many doors have a lock
Types of doors
A revolving door is a group of doors that turn in a circle as a person pushes one. The person can go through, but wind and rain cannot get in.
A blind door is a fake door that is really part of the wall. People use them to make a room look nice.
A doggie door is a small door for dogs or other small pets. They are usually on the bottom of people-sized doors.