One notable event in Ethereum's history is the hard fork, or split, of Ethereum and Ethereum Classic. In 2016, a group of network participants gained control of the smart contracts used by a project called The DAO to steal more than $50 million worth of ether.

The raid's success was attributed to the involvement of a third-party developer for the new project. Most of the Ethereum community opted to reverse the theft by invalidating the existing Ethereum blockchain and approving a blockchain with a revised history.