Insurance is a contract where you pay a little money at a time so you can be compensated later, especially in the case of a disaster.
Many people consider insurance to be making a kind of bet that bad things will happen: that's a good bet to make, because nobody is lucky forever. Legally, you need car insurance to drive. Without medical insurance, a serious illness could leave you broke. Life insurance is important so your family gets support when you die. House or apartment insurance will help if you have a fire. Insurance agents sell insurance policies, and they always have lots of customers.