This list is inspired by my time at Blockchain Oracles Summit in Berlin in June 2022 and being part of the Alliance of Decentralized Oracles Telegram chat.
Blockchain oracles are third-party services that provide smart contracts with external information. They serve as bridges between blockchains and the outside world.
Blockchains and smart contracts cannot access off-chain data (data that is outside of the network). However, for many contractual agreements, it is vital to have relevant information from the outside world to execute the agreement.
This is where blockchain oracles come into play, as they provide a link between off-chain and on-chain data. Oracles are vital within the blockchain ecosystem because they broaden the scope in which smart contracts can operate. Without blockchain oracles, smart contracts would have very limited use as they would only have access to data from within their networks. ~Source~
Blockchain oracles summit in Berlin
https://blockchainoraclesummit.io/
Meeting from 07/12/2022: The first call of the revitalized Alliance of Decentralized Oracles. https://youtu.be/2wWhvER_czw
Work in progress by ADO can be found here: https://github.com/adoracles/
https://github.com/adoracles/OracleBestPractices
https://tellor.io/whitepaper/#tellororacle