Insurance
Insurance is a way for people to protect themselves from potential risks. You buy insurance from an insurance company for some fee, and if an accident occurs, the company compensates you. Insurance companies are essentially a way for people to socialise their risks (e.g. illness, by pooling their money together. In DeFi, just as there are decentralised protocols built for people to lend out and/or exchange their tokens, there are insurance protocols where one can buy insurance against accidents on the blockchain — or put their funds in the insurance pools to cover others from losses in exchange for rewards.