All the air is removed from a sealed metal can. after the air is removed, the can looks as if it were crushed. why?

I remember learning about this in chemistry last semester.

The can looks like it was crushed because the outside pressure (aka atmospheric pressure) is pressing against the can that has no air in it, which is also called a vacuum in chemistry terms. The main thing to focus on is the atmospheric pressure that is pressing against the can and in the process, crushes it. Hopefully this makes sense. Good luck