cWBTC (Compound Wrapped Bitcoin) is a tokenized version of Bitcoin that is pegged 1:1 to Bitcoin and can be used as collateral in the Compound decentralized finance (DeFi) platform. By wrapping Bitcoin in the Ethereum blockchain, users can access the benefits of both assets simultaneously. cWBTC allows users to earn interest by lending out their Bitcoin while still maintaining ownership of the underlying asset. It provides a way for Bitcoin holders to participate in the DeFi ecosystem and earn passive income on their holdings.