EVM

The EVM (Ethereum Virtual Machine) is the sandboxed runtime every Ethereum node executes to run smart contracts. Every full node runs every transaction through its own EVM and must arrive at the same state — that's how consensus works at the execution layer. The crucial property is determinism: same inputs and same state always produce the same output, regardless of whose machine you're on. The second-order effect of the EVM was unintentional but enormous — by standardising bytecode, it let other chains (Polygon, BSC, Avalanche, Arbitrum) become "EVM-compatible" and inherit Ethereum's entire tooling and contract ecosystem with zero work. That's why Ethereum's moat isn't really the chain, it's the EVM.