Tellor (TRB) is a decentralized oracle protocol that strives to bring off-chain data on-chain. It functions by encouraging data reporters to supply accurate data on-chain, while also discouraging inaccurate reports through a system of disputes and slashing. The protocol is permissionless, meaning anyone, anywhere in the world, can become a data reporter using open-source software. Tellor's native token, Tributes (TRB), is used to align the interests of data reporters, oracle users, and community governance. The protocol aims to be flexible and robust, with the potential to support a variety of blockchain applications.

Tellor functions by encouraging data reporters to supply accurate data on-chain. When oracle users request the value of an off-chain data point, data reporters compete to add this value to an on-chain data bank, accessible by all smart contracts on the networks Tellor supports. The frequency with which data can be updated is limited only by how much and how often users "tip" the feed with TRB. Security is intended to be achieved through Tellor’s governance contract, which uses a simple dispute mechanism to achieve community consensus on the data being reported. Data reporters must stake TRB in order to report data and earn rewards, but they can be disputed and slashed, with their stake given to the disputer if they submit data the network deems incorrect.

Tellor strives to provide a solution for the "oracle problem" in the blockchain space, where off-chain data needs to be brought on-chain for smart contracts to use. This makes it potentially useful for a wide range of decentralized finance (DeFi) applications that require access to real-world data. For instance, a DeFi lending platform might use Tellor to access up-to-date price information for various cryptocurrencies, enabling it to adjust loan terms in real-time. Similarly, a decentralized insurance platform could use Tellor to access data about real-world events, such as weather conditions or flight delays, in order to process claims.

Tellor was launched in 2019 by a U.S.-based team consisting of Brenda Loya, Nick Fett, and Michael Zemrose. The team addressed the oracle problem on the Ethereum blockchain. Prior to founding Tellor, the team members had diverse backgrounds in blockchain, economics, regulation, and machine learning. The protocol has since expanded to support multiple networks, including Ethereum, Polygon, and Algorand. The Tellor network aims to be secured through its native token, Tributes (TRB), which aligns the interests of data reporters, oracle users, and community governance.