# What Is a Blockchain Oracle?

## What Is a Blockchain Oracle?

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Blockchain oracles are entities that connect blockchains to external systems, thereby enabling smart contracts to execute based upon inputs and outputs from the real world.&#x20;
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Oracles provide a way for the decentralized Web3 ecosystem to access existing data sources, legacy systems, and advanced computations. Decentralized oracle networks (DONs) enable the creation of hybrid smart contracts, where on-chain code and off-chain infrastructure are combined to support advanced decentralized applications (dApps) that react to real-world events and interoperate with traditional systems.\


Blockchain oracles connect blockchains to inputs and outputs in the real world.

![Oracle Input/Output Graph. ](https://assets-global.website-files.com/61163fe987f45b44cc88bc6a/61277245f4962c179dcab303_Hybrid%20Smart%20Contract.png)

**For example,** let’s assume Frank and Lucy want to set up a escrow bet on the outcome of a friendly football match. Alice bets $200 on the BLUE team, and Bob bets $200 on the RED team, with the $400 total held in escrow by a smart contract. When the game ends, how does the smart contract know whether to release the funds to Frank or Lucy? The answer is to link an oracle to fetch the data off-chain and validate the score on-chain, therefore validating who the winner is.
