A blockchain bridge, often called a crypto bridge, is a protocol or application that enables tokens and data to move between two separate blockchain networks. Because most blockchains are not natively interoperable, bridges act as connectors that let users and developers transfer value across ecosystems rather than staying confined to a single chain.
How bridges move assets across chains
In practice, bridging usually involves exchanging an asset on one chain for a corresponding representation on another. A common design is lock-and-mint: you lock tokens in a smart contract or custody system on Chain A, then an equivalent “wrapped” token is minted on Chain B. When you go back, the wrapped token is burned on Chain B and the original tokens are released on Chain A. This mint-and-burn accounting helps keep supply consistent across networks, so you are not creating extra value out of thin air, you are shifting where it can be used.
A well-known example is Wrapped Bitcoin (WBTC), which represents Bitcoin on networks that support smart contracts. By holding a bridged representation of BTC, users can access DeFi activities such as lending or liquidity provision in an ecosystem where native Bitcoin cannot directly participate.
Types, trade-offs, and common risks
Bridges can be centralized, relying on a custodian or federation to hold assets and approve transfers, or decentralized, using smart contracts and validation mechanisms to verify cross-chain events. Centralized bridges can be simpler and faster, but they introduce trust assumptions. Decentralized bridges can reduce reliance on a single party, but their smart contracts and verification logic add complexity.
Bridges matter because they expand liquidity and functionality across blockchains, making crypto more interconnected. At the same time, bridges are frequent targets for exploits, so understanding how a bridge secures locked funds and validates messages is essential for safer cross-chain use.