What is a brief description of the camera?

Answer 1A very brief and very over-simplified description is that a camera is:

1. a "box"

2. with a light sensitive media [film or electronic light sensing grid] at the back side,

3. with an opening [lens or pin hole] at the front to admit light from a subject and to form an image on the media,

4. and a method [a diaphragm to control the intensity of the light, and a shutter to control the length of time the light is allow to strike the media] of controlling the amount of light getting to the media.