Life Assurance is insurance of people's lives where it is certain that a payment will be made. That is, whereas e.g. non-life insurance might pay out if the contingency occurs that justifies payment (e.g. a fire in the case of fire insurance), in the case of life assurance pay out is certain because death is certain.

For example, in the United Kingdom there are life insurance policies that are with-profit (insured value increases as returns accrue on the underlying portfolios) endowment life insurance policies. They are either single-premium (policyholder makes one initial investment only) or multiple premiums (e.g. monthly premiums during the life of the policy). They pay out either in the event of the death of the policyholder or in the event of the maturity of the policy...but one or the other event will occur (is assured).