DAO is an organization where decisions get made from the bottom-up; a collective of members owns the organization. There are various ways to participate in a DAO, usually through the ownership of a token.
When a smart contract (DAO) is created and deployed, the only way to alter its “regulations” is through a community vote. Because the smart contract has to be defined using code-based logic, any attempts at changing the rules will fail unless the changes are decided upon through a vote.