[The DAO](https://en.wikipedia.org/wiki/The_DAO_(organization)) was a decentralized autonomous organization launched on the 📝Ethereum blockchain in April 2016 as an investor-directed venture-capital fund — its participants pooled ether, then voted on which proposed projects to fund, with the smart contract executing the disbursement and tracking returns.
At its peak the DAO held approximately $150 million in ether, making it the largest crowdfunding event in history at the time. In June 2016 an attacker exploited a reentrancy vulnerability in the smart contract and began draining funds — ultimately moving about a third of the assets into a child DAO that, by the same rules, would lock the funds for a period before they could be withdrawn. The Ethereum community responded with a hard fork that effectively reversed the theft, preserving the original chain as Ethereum Classic and producing the Ethereum we use today as the forked continuation.
The event is foundational in blockchain history for two reasons. It demonstrated the destructive potential of smart-contract bugs at meaningful scale, and it forced an unprecedented community decision about whether immutability could be overridden under sufficiently extreme conditions — a question whose answer (yes, by social consensus) continues to shape blockchain governance discourse.