On your insurance policy, you might have coverage for uninsured or underinsured motorists. This is important if you do end up getting struck by a motorist who didn't bother with insurance or who just stuck to the state minimum coverage. In both of these cases, you might find that the coverage or lack of coverage is insufficient for paying your bills related to the accident.
When some people buy a car insurance policy, they aren't always looking at the coverage amounts they are getting. Many only want a policy that is cheap and meets the minimum requirements of the state. However, this minimal coverage isn't always suitable for serious crashes.