The collision portion of an automobile insurance
policy pays for damage to your car in an accident, while the
comprehensive portion covers damage caused by other factors.
According to "Get a Financial Life" by Beth Kobliner (Simon
& Schuster), "Comprehensive insurance covers damage caused
by fire, flood, theft, tornado, and just about any other physical
damage that is not covered by collision. In all states both of these
coverages are optional. However, if you took out a loan to buy your
car or if you're leasing, the lender or dealer will require that you
purchase collision and comprehensive coverage."