Some protocols provide incentives for providing liquidity, often in the form of governance tokens or so-called LP tokens. These tokens, in turn, can be locked into yield farms, which reward users with more of the same token or with a different token. There is also often an external market for governance or LP tokens which can be quite profitable. Compound, for example, rewards liquidity providers with its governance token COMP. There are pools for COMP as well as a thriving market.