Cross-chain bridge: moving assets between networks

How Tokens Cross Networks

A cross-chain bridge is a protocol that lets value move between two separate blockchains. The standard pattern is lock-and-mint: you deposit tokens on Chain A, the bridge locks them there, and an equivalent amount of wrapped tokens is minted on Chain B for you to use. To go back, you burn the wrapped version, and the original is released on Chain A.

Bridges are the connective tissue of a multi-chain ecosystem. Without them, ETH on Ethereum and ETH on Arbitrum would be unrelated assets. Major bridges include the native rollup bridges (Arbitrum, Optimism, Base), specialized fast bridges (Across, Stargate, Synapse), and cross-ecosystem bridges (Wormhole, LayerZero, Axelar) that connect very different chains like Ethereum and Solana.

Bridges have been the single largest source of theft in DeFi history. Hundreds of millions have been lost to exploits of Wormhole, Ronin, Nomad, Harmony, and others, usually through validator-signing-key compromise or smart contract bugs. The fundamental issue is that bridges aggregate large amounts of value under custodial assumptions that vary by design. Before using a bridge, check who controls the locking contract, whether it uses MPC or multisig, whether it has been audited, and how it has performed under stress.