Renter's insurance is a policy for renters that covers the replacement value of possessions. Though your landlord probably carries insurance on the building you live in, that insurance is unlikely to cover your belongings: clothing, furniture, stereo, computer, and other personal possessions. In the event of a fire or break-in, you could still face repair or replacement costs.
Renter's insurance can include liability coverage, as well, to protect you if someone gets hurt at your residence. Renter's insurance may also provide legal defense costs.
In terms of coverage, most renter's policies are similar to homeowner's policies. A renter's policy should cover your furniture, clothing, TV, stereo, appliances, and other personal property.
Protection under your renter's insurance policy is fairly broad: for example, if your clothing is stolen from your car, your renter's policy will cover the replacement costs. However, you are only protected from hazards specifically listed in the policy. These typically include fire and lightning; windstorms; hail; explosion; riot or civil commotion; aircraft or vehicle damage; smoke damage; vandalism or malicious mischief; theft; falling objects; and artificially generated electrical current.