What is Ethereum?
Answer
Ethereum is a decentralized, open-source blockchain platform that features smart contract functionality — programs stored on the blockchain that execute automatically when conditions are met. Created by Vitalik Buterin (whitepaper 2013, mainnet launch July 2015). Key features: (1) Turing-complete EVM — the Ethereum Virtual Machine executes arbitrary smart contract code, enabling decentralized applications (dApps); (2) ETH (Ether) — the native cryptocurrency used to pay for computation (gas); (3) Proof of Stake — switched from Proof of Work to PoS in "The Merge" (September 2022), reducing energy consumption by ~99.95%; (4) Token standards — ERC-20 (fungible tokens), ERC-721 (NFTs), ERC-1155 (multi-token); (5) DeFi ecosystem — largest decentralized finance ecosystem by Total Value Locked (TVL); (6) Layer 2 scaling — Optimism, Arbitrum, zkSync, Polygon scaling solutions. Ethereum is the dominant platform for DeFi, NFTs, and smart contract development.