Zest is a Bitcoin lending protocol that operates on-chain and is open-source, aiming to make Bitcoin productive by creating a vibrant borrowing and lending ecosystem around BTC. It reduces counterparty risk by holding capital and issuing loans transparently on-chain, relying on smart contracts to handle pooled funds and ensuring secure and auditable transactions. Zest features two types of pools: Earn pools, where users earn a yield on their BTC, and Borrow pools, where users borrow against their BTC or Bitcoin assets, providing a decentralized and efficient solution for liquidity provision and utilization in the blockchain space.