What Is Interoperability in Blockchain?

Blockchains don’t talk to each other by default. Bitcoin’s ledger has no native way to see what’s happening on Ethereum, and Ethereum can’t natively read Solana’s state — a problem that got a lot more consequential as the number of active chains went from a handful to dozens, each specializing in something different. Interoperability is the umbrella term for the tools and protocols built to solve that: letting different blockchain networks communicate, transfer data, and move assets between one another despite each one running its own consensus mechanism, data format, and rules.

Several distinct approaches have emerged to bridge that gap. Cross-chain bridges — like Wormhole or Axelar — lock an asset on one chain and mint a representative token on another. Sidechains and layer-2 networks connect back to a main chain for security while running their own execution environment. Messaging protocols such as Cosmos’s IBC or LayerZero go a step further, letting smart contracts on different chains send data and instructions to each other directly, rather than just wrapped tokens.

Bridges specifically have become one of the most consistently exploited pieces of crypto infrastructure, because they hold large pools of locked value and depend on complex code to verify transactions happened correctly on the other side. The Ronin Bridge hack in 2022 (roughly $625 million) and the Wormhole exploit the same year (about $325 million) remain two of the largest thefts in crypto history, and both trace back to weaknesses in how a bridge verified cross-chain messages rather than a flaw in either underlying blockchain.

None of that has slowed the shift toward treating interoperability as core infrastructure rather than an optional feature. As the number of active chains keeps growing, a genuinely connected multi-chain environment — where liquidity, applications, and communities aren’t locked to a single network — is increasingly the assumption developers build around, even if the security track record of the bridges making it possible still lags the ambition.