Glossary · B
Bridge
A protocol that enables the transfer of assets or data between two separate blockchain networks. For example, a bridge allows you to move ETH from Ethereum mainnet to Arbitrum. Bridges are a significant security risk — cross-chain bridge exploits account for a large proportion of total DeFi losses.
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How Bridge works in practice
A bridge moves value between chains that cannot natively talk to each other. The usual design locks the asset on the source chain and mints a representation on the destination; burning the representation releases the original. What varies — and what determines the risk — is who or what guarantees that the locked reserves actually exist.
Worked example
You bridge 1 ETH from Ethereum to an L2. The bridge contract locks your ETH on Ethereum and credits 1 ETH on the L2. That L2 balance is a claim, and its value depends entirely on the lock contract remaining solvent and honest.
Figures are illustrative and chosen to be checkable, not live market data.
The mistake that costs people money
Bridges have been the single largest source of loss in DeFi by value. A bridged asset is not the original asset — it is a claim on a bridge, and it is worth exactly what that bridge's security is worth. Holding 'ETH' on a chain where ETH is not native means holding someone's IOU.
Bridge: common questions
- What is Bridge?
- A protocol that enables the transfer of assets or data between two separate blockchain networks. For example, a bridge allows you to move ETH from Ethereum mainnet to Arbitrum. Bridges are a significant security risk — cross-chain bridge exploits account for a large proportion of total DeFi losses.
- How does Bridge work in practice?
- A bridge moves value between chains that cannot natively talk to each other. The usual design locks the asset on the source chain and mints a representation on the destination; burning the representation releases the original. What varies — and what determines the risk — is who or what guarantees that the locked reserves actually exist.
- Can you give an example of Bridge?
- You bridge 1 ETH from Ethereum to an L2. The bridge contract locks your ETH on Ethereum and credits 1 ETH on the L2. That L2 balance is a claim, and its value depends entirely on the lock contract remaining solvent and honest.
- What do people get wrong about Bridge?
- Bridges have been the single largest source of loss in DeFi by value. A bridged asset is not the original asset — it is a claim on a bridge, and it is worth exactly what that bridge's security is worth. Holding 'ETH' on a chain where ETH is not native means holding someone's IOU.