t3rn is a Polkadot-based blockchain interoperability protocol that facilitates cross-chain transactions and enables trust-free collaboration between blockchains. It is a hosting platform for smart contracts that offers interoperability, fail-safe execution, and composability, allowing smart contracts to execute on multiple blockchains and be stored in a decentralized repository for anyone to use. The ultimate goal of t3rn is to create an ecosystem that rewards developers for their contributions and enables anyone to deploy an interoperable smart contract.