ELI5: Explain Like I'm 5

Assurance contract

An assurance contract is like a promise that a group of people make. People who agree to the assurance contract each give a bit of money. Then, if enough people join the contract, everyone who contributes gets their money back, and something extra for their trouble! But if not enough people join, then the people who gave money don't get it back. So, it's like a way for people to work together to get something they all want.