Chain ID

A Chain ID is a unique numerical identifier assigned to a specific blockchain network to distinguish it from others. Within the Ethereum ecosystem and EVM-compatible chains, this ID is essential for ensuring that transactions are processed only on the intended network.

When a transaction is signed, the Chain ID is incorporated into the transaction hash, effectively locking that transaction to the designated ledger. This prevents cross-chain replay attacks and allows wallets and nodes to identify which network a transaction belongs to.

For developers, correctly configuring the Chain ID is a critical step in protocol deployment to ensure compatibility with wallets like MetaMask. It serves as a fundamental piece of protocol physics, ensuring that decentralized finance operations do not accidentally spill over into incompatible environments.