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Bridge

In simple terms

A bridge is like a ferry that carries your cryptocurrency from one blockchain to another. It lets you move your digital assets between different blockchain networks so you can use them wherever you need.

Definition

A tool that allows you to transfer assets between different blockchains.

In depth

A bridge is a protocol that enables cross-chain asset transfers by locking assets on the source blockchain and minting equivalent wrapped tokens on the destination blockchain. Bridges typically use validators or oracles to attest to transactions and maintain a 1:1 peg between locked and minted assets, ensuring consensus across both chains. When you initiate a transfer, smart contracts on both blockchains coordinate to verify the transaction and release or burn tokens accordingly, allowing seamless interoperability between otherwise isolated blockchain networks.

How does Bridge work?

A bridge moves value between blockchains that cannot talk to each other directly. In the common lock-and-mint design, you send tokens to a contract on the source chain, which locks them. Off-chain watchers, a validator set, or a light-client proof observes that deposit and relays it to the destination chain, where a paired contract mints an equivalent wrapped token. Going back reverses the process: the wrapped token is burned and the original is unlocked. Other bridges instead use liquidity pools on both sides, paying you from a pre-funded pool rather than minting. Either way, the wrapped asset is a claim, not the original coin.

An example

Someone locks 1 ETH in a bridge contract on Ethereum. A relayer confirms the deposit and the destination chain mints 1 wrapped ETH to their address there. They use it in applications on that chain, then later burn it to unlock the original 1 ETH back on Ethereum. Throughout, the wrapped token's redeemability depends entirely on that locked ETH remaining secure and the bridge remaining operational.

Figures are illustrative only.

What beginners get wrong

  • Bridges have been among the largest hacking targets in crypto, with several individual exploits exceeding one hundred million dollars in losses.
  • Wrapped tokens are only worth the collateral backing them; if the bridge is drained or halted, the wrapped version can become unredeemable.
  • Selecting the wrong destination network in a bridge interface can send funds to an address you do not control on that chain.
  • Treating all bridges as equivalent overlooks large security differences between designs that verify proofs on-chain and those trusting a small multisig.

Related terms

Part of

What is cryptocurrency, and how does it work? — the subject page for cryptocurrency basics, with all 23 of its definitions in one place.

Educational only — not financial advice.