What is EVM?
Also called: Ethereum Virtual Machine
The EVM is the runtime that executes Ethereum smart contracts. Chains described as EVM-compatible run the same bytecode, so one contract and one toolchain can serve many networks.
In practice
EVM compatibility is why the same Solidity contract can deploy to Ethereum, Arbitrum, Base, Polygon, and Optimism with little change, and why wallets and libraries work across all of them. For a builder it means transferable skills: EVM experience earned on one chain counts on the others.