how does permissions work?

Answer 1

Did the idea of a descriptive question frighten you?

Unix permissions? Chmod, chown chgrp etc?
windows permissions
letting you children play in the mud?

Might get a useful answer if you post a useful question.
Mark

Answer 2

When you have permission to do something; then you can do it.
When you don't have permission to do something; then you CAN'T do it. :-) you have my permission to have a good day ;-)