Interoperability

Interoperability is the ability of different blockchains to exchange assets, data, and messages with one another, despite being separate networks with incompatible rules and no built-in awareness of each other. A blockchain is a closed system: Ethereum's consensus cannot natively verify what happened on Bitcoin or Solana, so making chains work together requires additional infrastructure — and that infrastructure is one of the hardest security problems in crypto.

The most visible interoperability tools are bridges, which lock an asset on one chain and issue a representation of it on another; wrapped bitcoin (WBTC) on Ethereum is a long-running example, letting BTC value participate in Ethereum's DeFi. Deeper approaches build interoperability into the protocol layer: Cosmos chains speak IBC, a standard that lets independent chains verify each other's state through light clients, while Polkadot connects parachains through a shared security layer, and messaging networks such as LayerZero and Chainlink's CCIP relay arbitrary data between ecosystems. For example, IBC allows tokens to move between Cosmos-based chains without a trusted custodian, because each chain cryptographically verifies the other's blocks.

A common misconception is that assets actually "move" between chains; nothing leaves its native ledger — bridges create IOU-like representations backed by locked originals, which is why a bridge hack can render the wrapped versions worthless. Several of the largest thefts in crypto history were bridge exploits, so interoperability today is a spectrum of trust models, from federations you must trust to light-client verification you can check.