Ethereum Virtual Machine (EVM)

The Ethereum Virtual Machine is the runtime every Ethereum node uses to execute smart contract code, defined precisely enough that all nodes reach identical results from the same inputs. Contracts are compiled to EVM bytecode and run on a stack machine whose every operation carries a gas cost, so computation is metered and an infinite loop simply runs out of gas rather than halting the network. Because the specification is public, many other chains and rollups implement the same instruction set and are described as EVM-compatible, which lets existing contracts and developer tooling be reused with little change. That shared surface also means a class of bugs reappears across every chain that copies it.