There are broadly two types of life insurance avialble to buy. There can be described thus:

Investment-type (aka 'permanent insurance' or 'life assurance').

These policies will definitely pay out at some time. Endowment policies pay out at the end of a specified term or on death if that happens during the term.

Whole of life policies pay out on death, whenever that occurs. Because the policy will definitely pay out at some time, they build up a cash value. It is this cash value that provides you with an investment. The protection element of investment-type policies is often very small.

Protection-only (aka 'term insurance' or 'temporary insurance').

These policies do not necessarily pay out at all. They pay out only if death occurs during a specified period (the term). If you survive, the policy pays out nothing.

If your main aim is to protect your dependants, term insurance is often the best type of life insurance to choose, because it's generally the cheapest way to buy a lot of cover.

For our purposes, we will be focusing on Investment type life insurance as this is where the majority of policies are.