Ethereum has pioneered the smart contract platform. Smart contracts are computer programs that will automatically execute actions necessary to fulfill an agreement between several parties online. This reduces the need for trusted intermediates between contractors, which lowers transaction costs while increasing transaction reliability.
Ethereum’s main innovation was designing a platform that allowed it to execute these smart contracts using the blockchain. This reinforces the already existing benefits of smart contract technology. Ethereum’s blockchain was designed to be “one computer for the entire planet,” theoretically it would be able to make any program more robust, censorship-resistant and less prone to fraud by running it on a globally distributed network of public nodes according to co-founder Gavin Wood.
Ethereum was described in the 2013 whitepaper by Vitalik Buterin.