YFI and yTokens

YFI

Yearn Governance token
Only 30,000 minted and already fully distributed
- Governance can mint more, if proposal to do so passes.

yTokens

When you deposit into any yearn service your deposit is wrapped and returned as a yToken representing the liquidity provided
For example, if you deposit DAI in y.curve.fi you will receive yDAI in return
Amounts of yToken and deposited token will differ since the yToken represents a share of a pool that is increasing in value
If you deposit a yToken into another yearn service you will get a yyToken back

yUSD

See our doc on yUSD for detailed info
LP token for yearn's yCRV yVault
aka yyCRV or yyDAI+yUSDC+yUSDT+yTUSD
When you deposit yCRV into the yVault you receive yUSD**** LP tokens
earns interest via yCRV, fees and yield farming rewards via the vault strategy

yCRV

LP token for yearn's Y pool at Curve.fi/y
Aka yDAI+yUSDC+yUSDT+yTUSD
Interest earning token representing your share of the Y pool composed of DAI, USDT, USDC, and TUSD