Liability insurance (also called third-party insurance) is a part of the general insurance system of risk financing to protect the purchaser (the "insured") from the risks of liabilities imposed by lawsuits and similar claims and protects the insured if the purchaser is sued for claims that come within the coverage of the insurance policy.
Originally, individual companies that faced a common peril formed a group and created a self-help fund out of which to pay compensation should any member incur loss (in other words, a mutual insurance arrangement). The modern system relies on dedicated carriers, usually for-profit to offer protection against specified perils in consideration of a premium
Liability insurance is designed to offer specific protection against third-party insurance claims, i.e., payment is not typically made to the insured, but rather to someone suffering loss who is not a party to the insurance contract. In general, damage caused intentionally as well as contractual liability are not covered under liability insurance policies. When a claim is made, the insurance carrier has the duty (and right) to defend the insured.
The purpose of liability insurance is to provide indemnity in respect of damages payable under law for personal injury to third parties or damage to their property.