If you run into someone's car from behind, who is at fault?

It's generally your fault and the other party can make a claim against your liability insurance. Car insurance features several components, including:

• Bodily injury liability and property damage liability
• Medical payments and personal injury protection
• Collision
• Comprehensive
• Uninsured/underinsured motorists coverage
• Extras, such as roadside assistance

Every state except New Hampshire requires drivers to carry liability insurance, although the minimum required amounts vary. Liability insurance pays for the damage you do to others when you cause an accident, including property damage and personal injury. However, in no-fault car insurance states, a driver's own insurer handles claims for injuries regardless of who was at-fault in an accident. No-fault laws were created to ensure prompt payment for medical expenses suffered by injured drivers and passengers.

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Comprehensive and collision coverage are optional, and some drivers go without it to save on car insurance rates. Collision coverage pays to repair or replace your vehicle if it's damaged in an accident -- even one that's your fault. Comprehensive, on the other hand, pays for damage to your vehicle that wasn’t caused by an accident, such as natural disasters, theft, vandalism or collision with an animal.

Medical payments or personal injury protection coverage pays for medical expenses and lost wages for you and your passengers who are injured in an accident. Sixteen states require personal injury protection coverage.

Uninsured motorist coverage pays your medical bills if an uninsured driver strikes your car, or if you are the victim of a hit-and-run. Similarly, underinsured motorist coverage kicks in when someone causes an accident, but doesn’t have enough auto insurance to cover the cost of all of your medical bills. Once the at-fault person’s insurance maximum has been paid out, your underinsured coverage pays for the remaining medical costs, up to your own limit.

For more, see car insurance basics.