In the United States, the most prevalent form of self-insurance is governmental risk management pools. They are self-funded cooperatives, operating as carriers of coverage for the majority of governmental entities today, such as county governments, municipalities, and school districts. Rather than these entities independently self-insure and risk bankruptcy from a large judgment or catastrophic loss, such governmental entities form a risk pool. Such pools begin their operations by capitalization through member deposits or bond issuance. Coverage (such as general liability, auto liability, professional liability, workers compensation, and property) is offered by the pool to its members, similar to coverage offered by insurance companies. However, self-insured pools offer members lower rates (due to not needing insurance brokers), increased benefits (such as loss prevention services) and subject matter expertise. Of approximately 91,000 distinct governmental entities operating in the United States, 75,000 are members of self-insured pools in various lines of coverage, forming approximately 500 pools. Although a relatively small corner of the insurance market, the annual contributions (self-insured premiums) to such pools have been estimated up to 17 billion dollars annually.
An insurance company may inadvertently find that its insureds may not be as risk-averse as they might otherwise be (since, by definition, the insured has transferred the risk to the insurer), a concept known as moral hazard. This 'insulates' many from the true costs of living with risk, negating measures that can mitigate or adapt to risk and leading some to describe insurance schemes as potentially maladaptive. To reduce their own financial exposure, insurance companies have contractual clauses that mitigate their obligation to provide coverage if the insured engages in behavior that grossly magnifies their risk of loss or liability.
An entity which provides insurance is known as an insurer, insurance company, insurance carrier or underwriter. A person or entity who buys insurance is known as an insured or as a policyholder. The insurance transaction involves the insured assuming a guaranteed and known relatively small loss in the form of payment to the insurer in exchange for the insurer's promise to compensate the insured in the event of a covered loss. The loss may or may not be financial, but it must be reducible to financial terms, and usually involves something in which the insured has an insurable interest established by ownership, possession, or pre-existing relationship.