The principle behind T.OS is the establishment of a commercial payment system that utilizes digital currency. This will be the first such system in the history of the world. The solution comprises two coins. The TOS coin, or TOSC, is a regular cryptocurrency coin, which is not used for commerce, but can be exchanged on regular exchanges to any other digital currency. Its value may appreciate or depreciate and that is why it can't be used for commerce.
The operational token of the Theta protocol. TFUEL powers on-chain operations like payments to relayers for sharing a video stream, or for deploying or interacting with smart contracts. Relayers earn TFUEL for every video stream they relay to other users on the network. You can think of Theta Fuel as the 'gas' of the protocol. At Mainnet launch on March 15th, TFUEL will be created as a native token on the Theta blockchain.