Ethereum (ETH)

A network where a transfer is just one special case: nodes execute programs recorded on chain, and the result becomes part of the shared state. Those programs are smart contracts, and the environment that runs them — the Ethereum Virtual Machine — has had its instruction set copied by dozens of other chains. Bookkeeping uses accounts with balances rather than Bitcoin's unspent outputs.

Computation is paid for in gas, denominated in ETH: what an operation costs depends on its complexity, not on the sum being moved. Part of each fee is burned, part goes to whoever proposed the block. Since 2022 consensus runs on proof of stake — validators post a deposit to propose blocks, and losing that deposit is the penalty for misbehaviour.

Most of decentralised finance, most non-fungible tokens and most dollar tokens grew on this platform: one shared issuance standard made every new asset compatible with wallets and exchanges already written. Expensive computation has been pushed out to second-layer networks that execute off-chain and post only proofs back to the base chain.

EVM compatibility became the industry default: a contract written for it moves to rival chains with little or no rewriting.