Bridge

A protocol that moves assets or messages between two blockchains.

A bridge connects two blockchains, allowing assets or messages to move between them. The typical mechanism: lock tokens on chain A, mint wrapped representations on chain B. To move back, burn on B, unlock on A. Bridges are responsible for verifying that lock and burn events actually happened.

Bridges are the highest-risk surface in crypto. Over $2.5B has been stolen from bridges since 2021 (Ronin, Wormhole, Nomad, Harmony, Multichain). The attack surface combines smart contract risk with validator trust assumptions — bridges with small validator sets are particularly vulnerable. Trust-minimized bridges using light clients or zk proofs are improving the security model.