Solidity

Solidity is the dominant language for writing smart contracts on Ethereum and every EVM-compatible chain (Polygon, Arbitrum, BSC, Optimism). Syntactically it looks like JavaScript with types — function, mapping, uint256, address — but semantically it's closer to a constrained systems language: every storage write costs money (gas), there's no garbage collector, and a single integer overflow can drain millions. Alternatives exist (Vyper for Ethereum, Move for Sui/Aptos, Rust for Solana), but Solidity has the ecosystem — every Ethereum tutorial, library, and audit firm speaks it natively.