What happens during switching?

Hello, fellow Redditors!

Apologies if this is a stupid question. I do not have any friends or relatives with DID but I find this condition extremely interesting, and I’m trying to learn how it works.

What happens when you suddenly switch? Let’s say, your alter is minding their own business, and something triggers a switch. When you come out, what do you feel?

Do you have any context on the situation? As far as I know, what your alter sees, other alters see it as ‘dreams,’ so it may give the new alter some info?

Does your mind fill the memory gaps your other alters used? What did you do before you were diagnosed, if you didn’t know what had happened?

Thanks in advance! <3