A blockchain bridge is a protocol or service that communicates asset or state information between otherwise separate blockchain networks and enables corresponding value or messages to be represented or acted on across them.
Asset bridges commonly lock or otherwise account for tokens on a source chain and mint or release a corresponding representation on a destination chain. Other designs burn and mint, use liquidity pools, or pass verified messages without creating a wrapped asset. Security depends on how the bridge verifies events on each chain, which can involve validators, multisignature committees, light clients, zero-knowledge proofs, or other mechanisms.
A bridge usually coordinates state or representations across separate ledgers. The identical token object does not travel between ledgers. SBMP-01 classifies many bridge-created stablecoin tokens as represented claims outside base stablecoin issuance.
Bridges expand stablecoin availability across networks but introduce additional smart-contract, validator, custody, and verification risks and can create double-counting problems in supply statistics.
A bridge can lock native stablecoins on one chain and mint an equivalent wrapped representation on another chain until the representation is returned and redeemed through the bridge.