$ETH is a decentralized, open-source blockchain platform that enables smart contracts and decentralized applications (dApps). Launched in 2015 by Vitalik Buterin and others, Ethereum introduced the concept of programmable blockchain functionality beyond simple transactions. Its native cryptocurrency, Ether (ETH), is used to pay for transactions and computational services on the network. Ethereum transitioned from Proof of Work to Proof of Stake in 2022 with "The Merge," making it more energy efficient. It supports a vast ecosystem of DeFi, NFTs, and Web3 innovations.