Synthetix started out as a stablecoin called Havven in 2018, and has since grown into one of the Ethereum ecosystem's most prominent derivatives projects.
Specifically, Synthetix is a derivative liquidity protocol that enables the creation of "synthesizers" (or synthetic assets) that can be traded in a decentralized manner without permission.
Synths allow traders to profit from asset exposure without having to hold the assets directly. Synthetix's currency synths, such as sUSD and sEUR, are among the company's most popular synths today.