Synthetix is a decentralized platform on Ethereum that allows users to create on-chain synthetic assets (known as Synths) that track the value of real-world assets. Originally begun as a stablecoin called Havven, the project rebranded to Synthetix and expanded its scope before it launched on Mainnet in February 2019.
SNX is the native token of Synthetix. Token holders can lock in SNX and/or ETH as collateral to mint Synths, which are freely tradeable ERC20 tokens. Transaction fees from Synths exchanged on Synthetix.Exchange, Synthetix’s non-custodial DEX, go directly to SNX holders and/or Synth minters. This effectively incentivizes the creation of Synths and gives value to the underlying collateral, namely the SNX token.
In summary, Synthetix itself is mainly a Decentralized Exchange (DEX) but also functions as a platform for the issuance of synthetic assets (Synths).