How do Car insurance exclusions work?

Well, they do just that they ''exclude'' (will not cover/pay for) certain things/happening or persons. A policy (for example) with an excluded driver, will not cover any losses that occured when that driver was driving the vehicle. An exclusion (again for example) of an 'intentional act by an insured' will not cover the insured intentionally driving their vehicle into a tree.......If you would like to be more specific as to a certain exclusion perhaps I could be of greater assistance to you.