> ## Documentation Index
> Fetch the complete documentation index at: https://docs.polygon.technology/llms.txt
> Use this file to discover all available pages before exploring further.

# Getting started

> An explanation of blockchain oracles and how they connect smart contracts to external data on Polygon.

Smart contracts cannot access data from outside their blockchain network. An oracle is the mechanism that bridges this gap, connecting a blockchain or smart contract to external data sources.

Oracles are services that fetch real-world information and deliver it onchain, triggering state changes when predefined conditions are met. Inbound oracles bring off-chain data to the blockchain. Outbound oracles do the reverse, notifying external systems when an onchain event occurs.

On Polygon, oracles are commonly used for price feeds in DeFi protocols, randomness for gaming, and real-world event data for prediction markets.

## Available oracle integrations

* [Chainlink](/tools/oracles/chainlink): decentralized price feeds and data aggregation.
* [Chronicle](/tools/oracles/chronicle): verifiable, cost-efficient price oracles.
* [Supra](/tools/oracles/supra): pull and push oracle integrations with high-frequency data.

## Further reading

1. [What is the blockchain oracle problem?](https://blog.chain.link/what-is-the-blockchain-oracle-problem/)
2. [What is a blockchain oracle?](https://cryptobriefing.com/what-is-blockchain-oracle/)
3. [Getting decentralized price data with Chainlink](https://docs.chain.link/docs/get-the-latest-price)