Inter-Blockchain Communication (IBC) is an open-source interoperability protocol that lets independent blockchains send authenticated messages to each other. Rather than “bridging” assets by trusting a third party, IBC defines a standardized way for chains to transport data packets and verify that those packets were committed on the source chain.
What IBC does and where it’s used
IBC is best known from the Cosmos ecosystem, where many application-specific blockchains need to coordinate without sharing the same state or validator set. With IBC, one chain can request an action on another chain by sending a message, such as transferring a token, triggering a smart contract call, or passing governance and staking-related information. Importantly, IBC is designed to be general-purpose, it can carry any kind of data as long as both sides understand the encoding.
In practical terms, IBC underpins common cross-chain user experiences, such as moving assets from one IBC-enabled chain to another, routing liquidity across multiple networks, or allowing wallets and apps to interact with multiple chains through a consistent transport layer.
How IBC works at a high level
IBC separates transport and authentication. Chains establish an IBC connection and open channels between specific modules (for example, a token transfer module). When Chain A sends a packet to Chain B, Chain B verifies cryptographic proofs that the packet was included in Chain A’s state. This verification is typically done using light client logic, so Chain B can check Chain A’s consensus without fully running Chain A.
Relayers, off-chain services, help by transmitting packets and proofs between chains, but they do not need to be trusted to tell the truth because the receiving chain verifies the proofs on-chain.
IBC matters because it provides a standardized, verifiable foundation for cross-chain communication, enabling more modular, connected blockchain ecosystems while reducing reliance on trusted intermediaries.