A DAO is a Decentralized Autonomous Organization. Participating in the governance of a DAO can happen from anywhere that can read/write to the blockchain, and the rules are autonomously enforced across all participants because they are encoded in the blockchain.
The DAO is a DAO specifically designed to raise money for other DAOs. The unique thing about it over other crowdfunding platforms is that voting rights are implemented in an Ethereum contract hence enforceable with no central authority.