What is a DAO in Web3?

Could you please explain what a DAO stands for in the context of Web3? I've heard a lot about this concept lately but still have some uncertainties. Is it a type of organization? Or a technological tool? And how does it fit into the broader Web3 ecosystem? I'm particularly interested in understanding its role in decentralization, governance, and potential use cases. Could you elaborate on these points and provide some examples, if possible? Thank you for your time and assistance.