The Inter-Blockchain Communication Protocol (IBC) is a protocol that handles authentication and transport of data between two blockchains, allowing for cross-chain communication. It provides a permissionless way for relaying data packets between blockchains and can work with a wide range of blockchains or state machines. IBC is essential for application-specific blockchains like those in the Cosmos network, offering a standard communication channel for applications on two chains that need to communicate.
IBC provides cross-communication through a decentralized network of independent and interoperable chains. Through the IBC, an 'internet of blockchains' that provides scalability is possible. The transport layer (TAO) provides the necessary infrastructure to establish secure connections and authenticate data packets between chains, while the application layer defines exactly how data packets should be packaged and interpreted by the sending and receiving chains.