YFII is a fork of the YFI cryptocurrency that has a fixed supply of 40,000 tokens. A blockchain fork is when a group of people disagree on what to do about a blockchain and it breaks into two different chains, with similar code. YFII forked from YFI in July 2020 by people interested in a certain liquidity pool reward calendar. They also wanted to build new features that were rejected in a close vote within the original YFI community. In response, a group of people copied the YFI code and made YFII with some slight modifications. Essentially YFII users invest into either CURVE or Balancer liquidity pools and earn rewards for offering their crypto as collateral for a DeFi exchange. With such a low supply and no possibility of ever making more, YFII has maintained a fairly high price per coin from the beginning.