Bridge

A bridge is infrastructure that connects two blockchains so assets or messages can move between them, despite the chains having no native ability to read each other's ledgers. The dominant design is lock-and-mint: you deposit an asset into the bridge's contract or custody on the origin chain, and the bridge issues a corresponding "wrapped" token on the destination chain; burning the wrapped token later releases the original. Nothing physically crosses — the bridge maintains a claim on locked collateral.

What differs between bridges is who attests that the deposit really happened. Some rely on a small committee of validators or a multisig (trusted), some on optimistic designs with fraud-challenge windows, and some on light clients or zero-knowledge proofs that verify the origin chain cryptographically (trust-minimized). For example, bridging USDC from Ethereum to another network typically means locking it in a contract and receiving a bridged representation minted on arrival, usable in that chain's apps until you bridge back.

Bridges are historically crypto's most dangerous infrastructure: because one contract or key set guards the collateral backing every wrapped token, they are concentrated honeypots. The Ronin bridge lost roughly 600 million dollars in 2022 when attackers compromised a majority of its nine validator keys, and Wormhole lost hundreds of millions to a signature-verification bug the same year. A common misconception is that a bridged token is the same asset as the original; it is an IOU whose value depends entirely on the bridge staying solvent and honest, which is why cautious users prefer canonical or trust-minimized bridges and avoid leaving large balances in wrapped form.