Interoperability
Interoperability is the ability of different blockchains to communicate, exchange data or value, and support applications that span more than one network.
Why blockchains are not interoperable by default
Each blockchain keeps its own ledger and reaches consensus only about its own transactions. It has no built-in way to know what happened on another chain. A smart contract on Ethereum cannot check a Bitcoin balance, and two Layer 2 networks do not automatically share state. Without extra infrastructure, every chain is an island with its own users, liquidity and apps.
How interoperability is achieved
Bridges move tokens by locking or burning them on one chain and issuing them on another. Messaging protocols pass arbitrary data, so an app on one chain can trigger a contract on another. Some ecosystems are designed for interoperability from the start: Cosmos chains can communicate through the IBC protocol, and Polkadot connects its parachains through a shared relay chain. Rollups on Ethereum share a common settlement layer, which helps them interact.
Oracles are related: they bring off-chain data, such as prices, onto a blockchain, which is another form of connecting systems.
Why it matters
Better interoperability lets users move funds to where fees are lower or apps are better, keeps liquidity from being split into isolated pools, and lets developers build applications that combine features of several networks.
The trust trade-off
Every connection between chains needs someone or something to confirm what happened on the other side. That might be a small group of signers, a set of validators, light clients or cryptographic proofs. The weaker this verification, the easier it is to fake a message and drain funds, which is why cross-chain bridges have been among the most costly targets of hacks. A system of connected chains can only be as secure as its weakest link.
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Frequently asked questions
Is interoperability the same as a bridge?
A bridge is one tool for interoperability. Interoperability is the broader goal, which also includes messaging protocols, shared standards and native cross-chain designs.
Can Bitcoin interact with other blockchains?
Not natively in a programmable way. It is usually connected through wrapped tokens, bridges or federated systems, each with its own trust assumptions.
Why don't all chains use one common standard?
Chains differ in consensus, data formats and security models, and no single protocol fits all of them, so several competing approaches exist.
Related terms
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