Insurance, in law and economics, is a form of risk management primarily used to hedge against the risk of catastrophic financial loss. Insurance is defined as the equitable transfer of the risk of a potential loss, from one entity to another, in exchange for a premium and duty of care. Insurer, in economics, is the company that sells the insurance. Insurance rate is a factor used to determine the amount, called the premium, to be charged for a certain amount of insurance coverage.

From the point of view of the insurance company there are four general criteria for deciding whether to insure events or not.

1. There must be a larger number of similar objects so the financial outcome of insuring the pool of exposures is predictable. Therefore they can calculate a "fair" premium.
2. The losses have to be accidental and unintentional (i.e., on the insured's part).
3. The losses must be measurable, identifiable in location and time, and definite. An insurer also requires that losses cause economic hardship. This so that the insured has an incentive to protect and preserve the property to minimize the probability that the losses occur.
4. The loss potential to the insurer must be non-catastrophic, i.e., it cannot put the insurance company in financial jeopardy.

Losses must be uncertain of occurrence.