Overview
A bridge is a protocol that enables the transfer of assets or data between different blockchain networks. Because blockchains do not communicate natively, bridges lock tokens on the source chain and mint a representation of them on the destination chain, or relay messages between chains. Bridges are the connective tissue of the multi-chain ecosystem, including the many chains of the Layer 2 landscape.
How It Works
Most bridges follow a lock-and-mint or burn-and-mint pattern: a user deposits assets into a contract on chain A, and the bridge operator or relay network verifies the deposit and mints wrapped tokens on chain B. The wrapped tokens can later be redeemed for the original by proving their burn on chain B. Trust models range from a single federated operator to decentralized validator sets, which determine how secure and censorship-resistant the bridge is.
Why It Matters
Bridges unlock liquidity across ecosystems but are also the most attacked infrastructure in crypto: a compromised bridge can drain hundreds of millions of dollars. Their security depends on the number and honesty of the parties controlling them, making "which bridge can I trust" a crucial question for users. Understanding bridge design explains both the value and the risk of cross-chain activity.
Related Concepts
Bridges connect Layer 2s to their base chain and link separate Layer 1s. They are part of the interoperability stack alongside Messaging Protocols like LayerZero, and their security assumptions are a core topic in chain evaluation.