What is Ethereum?
Ethereum is a programmable blockchain — a global computer that runs smart contracts. It powers most of DeFi, NFTs, and DAOs.
Where Bitcoin is digital money, Ethereum is more like a global computer. It launched in 2015 and introduced smart contracts: programs that run automatically on the blockchain.
This unlocked entirely new categories of crypto: decentralized finance (DeFi), non-fungible tokens (NFTs), decentralized autonomous organizations (DAOs), stablecoins, and countless apps built on top of the network.
Ethereum's native currency is ether (ETH). You use ETH to pay "gas fees" — the cost of running computations on the network. Gas fees can fluctuate wildly with demand.
Most of crypto's real-world activity happens on Ethereum or one of its Layer 2 scaling networks (Arbitrum, Optimism, Base). When people talk about "on-chain" activity, they usually mean Ethereum.