pension plan
Most people cannot work forever, yet they may live decades after they stop. A pension plan is a long-term arrangement — usually set up by an employer, a union, or the state — that sets money aside during a person's working years so they have income in retirement. It is one of the great inventions for turning a working lifetime into a secure old age.
The core mechanism is simple in spirit: while you work, contributions (from you, your employer, or both) flow into a pool; that pool is invested; and in retirement it pays out, ideally for the rest of your life. A funded plan holds real assets earmarked for the promises; a pay-as-you-go (unfunded) plan, common for state pensions, instead pays today's retirees from today's workers' contributions. The plan's design — who pays in, how the benefit is determined, when you can retire, what happens if you leave or die — is written in its rules and tested constantly against its money.
Pension plans are a central field of actuarial work. Actuaries estimate how much must be set aside today to meet promises decades away, which requires projecting salaries, retirement ages, withdrawals, investment returns, and how long people will live. The honest caveat: a pension is only as secure as its funding and its sponsor. A generous promise on paper means little if the contributions, investments, or the sponsoring employer cannot back it — which is why pension funding rules and actuarial valuations exist.
A factory sets up a pension plan: each year the company and worker each pay in a slice of pay, the money is invested, and at 65 a worker receives a monthly pension for life. An actuary checks every year whether the assets the plan holds are enough to cover the promises already earned — and tells the company how much more to contribute if they fall short.
Set money aside while working, draw income while retired — backed by real funding.
A pension promise is not the same as money in the bank. Its security depends on whether the plan is properly funded and the sponsor stays solvent — which is exactly what funding rules and regular actuarial valuations are meant to police.