Marinade.Finance is a non-custodial liquid staking protocol built on Solana. You can stake your SOL tokens with Marinade using automated staking strategies and receive "marinated SOL" tokens (mSOL) that you can use in decentralized finance (DeFi).
The price of mSOL goes up relative to SOL each epoch with rewards being accrued into the underlying staked SOL.
You can withdraw your SOL at any time by unstaking and waiting for the unlock period (2 epochs) or immediately with a small fee. You can also directly exchange between mSOL and SOL on secondary markets at the current rate.

Timeline
Further reading
Cooking with governance: Introducing Marinade Non-fungible Chefs
Marinade Finance
Web
February 18, 2022