Strategies are the most atomic unit of investment activity on the Affine protocol. Strategies can be broken into three general categories:
Token strategies are the most obvious and straightforward stategies. These stategies simply let users buy and hold crypto-assets directly or through wrapped versions of these assets. For instance, users could buy Bitcoin, Ethereum, MATIC -- or their wrapped versions -- and more. Taken together, baskets that contain token strategies allow users to hold (long position) and gain price exposure to the underlying assets. There can also be short positions as well.
Lending strategies are slightly more complex and allow users to participate in some of the true innovations in the DeFi ecosystem. These stategies allow users to provide funds like USDC to protocols such as Aave and Compound which are then lent out via said protocols. You can learn more about DeFi lending protocols here.
While related to lending strategies, liquidity pool strategies are slightly distinct in that you are providing liquidity to support a market. Typically, you do this by providing 2-sided liquidity so that market participants can exchange two tokens. Take, for instance a pool of MATIC and USDC: In this example, you would provide both MATIC and USDC into the pool. By providing this capital in the form of those two assets, you earn a portion of the fees that are earned when swapping those two assets. You can learn more about how liquidity pools work in detail here and here.