A more thorough explanation:

Coinsurance is an agreement between an insurance company and the person they insure. It means that the person who is insured agrees to pay a certain percentage of the cost of something that is covered by their insurance policy. The insurance company will then pay the rest of the cost.

For example, let's say you have health insurance with a coinsurance plan of 70/30. This means that you are responsible for paying 30% of the cost of your medical bills, and your insurance company will pay the remaining 70%. However, this only applies after you have paid your deductible, which is a certain amount of money that you have to pay before your insurance company starts paying for anything.

Another example of coinsurance is in property insurance. If you have a home insurance policy with a coinsurance clause, it means that you agree to insure your home for a certain percentage of its value. If you don't insure your home for that amount and something happens, like a fire or a flood, your insurance company may only pay a percentage of the cost of the damage.

Coinsurance is a way for insurance companies to share the risk with the people they insure. By agreeing to pay a percentage of the cost, the insured person is taking on some of the risk themselves, which can help keep insurance premiums lower.