Blockchain oracles sound like something out of ancient Greek mythology, and in some ways they function in a similar role. In ancient stories, people didn't have enough information to make decisions and turned to oracles for information beyond their understanding.
Similarly, Blockchain like Bitcoin and Ethereum, do not have easy access to information outside the chain, so there is no direct way to validate the terms on which Smart Contracts are based. An oracle is, in simple terms, a translator of information provided by an outside platform.
Oracles provide the data necessary to trigger smart contracts to be executed when the initial conditions of the contract are met. These oracles are the only way for Smart Contracts to interact with data outside the Blockchain environment.
Oracles are critically important. Just as ancient stories could never have happened without appropriate external information, Smart Contracts cannot function without a data source. Without access to these sources of information, the use cases for smart contracts are a tiny fraction of their potential.
One of the most likely future trends is the development of a unified and integrated platform for communication between Blockchain and the outside world. Many projects are trying to address this challenge, such as Cosmos and ChainLink.
