Splitting principal and interest
rDai (redeemable DAI) allows you to invest your money in an Interest generating pool, used for collateralized loans. You still hold on to the exact amount you invested, and can spend and transfer it at will.
You also decide who benefits from the generated interest: yourself, a community fund, a charity, or a dApp you are using.
rDAI is a fungible ERC20 token, meaning you can send any amount to any user, and they can always redeem it 1:1 for DAI