This optional section of the policy pays for damage to your vehicle. States do not require you purchase these coverages, but if you have a car loan, your lender will require you to until the loan is paid off.
Comprehensive pays for damage to your vehicle, other than collision--such as fire, theft, falling objects, explosion, earthquake, wind, hail, flood, vandalism, and contact with animals like birds and deer. It also pays for cracked windshields--with some companies offering glass coverage without a deductible.
Collision pays for damage to your car resulting from a collision with another vehicle, object, or as a result of flipping over. It also covers damage caused by potholes.
Even if you're at-fault for the accident, your collision coverage will reimburse you the costs of repairing your car, minus the deductible. If you are not at-fault, your insurance company may try to recover the amount paid from the other driver's insurance company. If they are successful, you'll be reimbursed for the deductible.