Question: I hit a large rock (maybe it would be considered a boulder) in the road. Is this comprehensive or collision?
Answer: If the boulder was already in the roadway and you ran into it with your vehicle, then it would be considered a collision with an object and thus go under the collision portion of your car insurance policy.
Collision covers you when you hit, or are hit, by another car. It also covers when you collide with inanimate objects; whether it is a fence, mailbox, house, curb, tree or large rock.
Comprehensive covers you for events that collision does not, such as vandalism, fire, theft and natural occurrences such as wind, hail or water damage. Comprehensive coverage covers if you sustain damage from an animal, such as a deer or dog. Also, comprehensive covers objects that fall on your vehicle. (See "Acts of God and your car insurance")
So, if the boulder had fallen on your car, as you drove under it, then it normally would be found to be a comprehensive claim. But the rock rolling into the side of your car or you hitting it because it was situated in the road where you couldn’t go around it is a collision claim.
A collision claim is more likely to raise your rates than a comprehensive claim. Comprehensive claims are usually due to situations beyond your control so state laws and/or car insurance company guidelines many times don't allow surcharges for these types of claims. You can contact your state's insurance regulator to find out more about what types of accidents can be surcharged for in your state.
When you make a collision claim, the deductible you picked at the inception of your auto insurance policy will be due. If the damage to your car were minor, you may first want to take it to a mechanic and get an estimate on the cost of repairs. If it costs less than your deductible amount to fix your car, then there is no need to make a claim since your insurer won’t pay for any repairs under your deductible amount.
If the cost is more than your deductible, but just barely, then you may still want to pay out-of-pocket for the repairs so that the claim will not affect your future car insurance rates.
But if your car sustained a great deal of damage and will cost a lot to repair, then normally it’s wise to use your collision coverage to have your car insurance company pay for the cost of repairs above your deductible amount; that is why after all you do carry the coverage, so you won’t be stuck with costly repairs after an auto accident.