Photography literacy. What is the "back" of the camera?

CCD is the digital back.

It is more convenient to change the film if the back is used.

For example, you are a camera without backup.

So if you want to change before the other films are finished.

For example, you are installing colors now.

But have you used up this roll of film?

But now you want to make a black-and-white movie.

So change to black and white film.

Then you must throw away what you left behind, or replace it in a dark room.

If you have a back (at least two backs)

So you put a black and white one and a color one.

Just replace the back when you replace it.

Do you understand this explanation?