There are two components in vehicle liability insurance, bodily injury  coverage and property damage coverage. These components always included together. In US, some states don't require the vehicle owner to carry car insurance, they may be paid to the state instead, such as Virginia. Meanwhile, New Hampshire and Mississippi offers the vehicle owners to post cash bonds. Insurance premium is usually determined by the type of covered vehicle, driver's age and gender, driving history, and vehicle storage. Vehicle liability insurance is necessary for anyone who owns and drives vehicle(s), it's also required by law in most situations. 

Liability coverage have different limits in the policy, which are:

You have to make sure to meet the state's minimum required limits. The higher the limits, the better you get protected. The reason is, if you accidentally cause damage that exceeds the limits of your coverage, you have to pay the rest expenses. Don't hesitate to talk with an insurance agent about liability coverage limits that suits for you.