Yield is an APY token. It rewards holders with an interest paid every 4 hours. The rewards are paid out without the need for staking, simply hold the token in your wallet. It is based on APY tokens, but have it's mechanism changed and a tier system added to it. The point of the tier system is to make it more sustainably (tier 1-100, level 100 gets 200%APY, level1 gets 1.1%) and also reward loyal holders. For advancing you need to hold tokens without selling more than 15% of your balance in a 48 hour period.