Hi i am sorry i know this is a stupid question but what is a mite?

I would like to research this subject due to my bee's might possibly have them.

I have a hive that has one or two bee's that i notice have chewed up wings on a frame.

I asked someone and they said they were probably mites.

I just have a few bees that have this issue.

What is the threat level on these?

Can i see what they look like so i can identify them?

Thanks for all of the replies i feel that i will get a lot.

P.s. why do they say not to use store bought powdered sugar?