Insurance is a term in law and economics. It is something people buy to protect themselves from losing money. People who buy insurance pay what is called a premium (often paid every month) and promise to be careful (which is called a "duty of care"). In exchange for this, if something bad happens to the person or thing that is insured, the company that sold the insurance will pay money back. (However, there are some times when the company will not have to pay money back, such as if the person was not careful.)
Types of insurance [change]
There are different kinds of insurance. One kind is called "fire insurance". It pays people if their property catches on fire and burns down. Another kind is called "life insurance", which pays somebody else (called the "beneficiary") money if the person who has life insurance dies or becomes seriously ill.
Actuaries are the people who figure out how much the premium should be. They balance how much the insurer might have to pay out against the chances of having to pay out. If an actuary thinks that there is a big chance that the company will have to pay out, he will make the premium higher.