The cost of insurance, in practice, is determined by mortality tables which are used in conjunction with the health and family history of the individual applying for a policy in order to determine premiums and insurability.

The insurance company receives the premiums from the policy owner and invests them to create a pool of money from which it can pay claims and finance the insurance company's operations. The majority of the money that insurance companies make comes directly from premiums paid, as money gained through investment of premiums can never, in even the most ideal market conditions, vest enough money per year to pay out claims.[citation needed] Rates charged for life insurance increase with the insurer's age because, statistically, people are more likely to die as they get older.