> For the complete documentation index, see [llms.txt](https://dzhelezov.gitbook.io/hydra/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dzhelezov.gitbook.io/hydra/docs.md).

# Overview

Introducing Hydra, a GraphQL query node for substrate chains

## Bird-eye overview

[Hydra](https://joystream.org/hydra) has two principal components: Hydra Indexer and Hydra Processor. Hydra Indexer ingests raw data from a substrate chain. Hydra Processor is responsible for transforming the raw data into domain-level entities as defined in `schema.graphl` and the event handlers, both provided by the user. `hydra-cli` provides additional scaffolding and codegen tooling for running and developing a Hydra Processor tailored for the provided schema file.

![Hydra Indexer (top) and Hydra Processor (bottom) data flows](https://1243191775-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MNiNoYZdwb5yBRUDc-q%2Fsync%2Fe587479ff22ad79886861487b2734b6556302d10.png?generation=1607096932683871\&alt=media)

## What's next?

* Explore live Hydra Indexer  [playground](https://indexer-kusama.joystream.app/graphql) and query Kusama events and extrinsics
* [Install](/hydra/install-hydra.md) Hydra toolkit 
* Hydra [tutorial](/hydra/quick-start.md): spin a query node in under five minutes
* Look at the [examples](/hydra/docs.md) 
* Learn how to define your own data [schema](/hydra/docs/schema-spec.md) and [mappings](/hydra/docs/mappings.md) to run a Hydra Indexer