# Introduction

Substreams is a powerful indexing technology, which allows you to:

* Extract data from several blockchains (Solana, Ethereum, Polygon, BNB...).
* Apply custom transformations to the data.
* Send the data to a place of your choice (for example, a Postgres database or a file).

<figure><img src="https://2510971185-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FerQrzMtqELZRGAdugCR2%2Fuploads%2Fgit-blob-4ae1522c7a03abbb8b59d8b5d5b0bbfa722e4de1%2Fsupported-chains.png?alt=media" alt="" width="100%"><figcaption></figcaption></figure>

**You can use Substreams packages to define which specific data you want to extract from the blockchain**. For example, consider that you want to retrieve data from the Uniswap v3 smart contract. You can simply use the [Uniswap v3 Substreams Package](https://substreams.dev/packages/uniswap-v3/v0.2.10) and send that data wherever you want!

### How Does It Work?

Watch the following video and visit the [Getting Started](https://docs.substreams.dev/getting-started) to learn more about how Substreams works.

{% embed url="<https://www.youtube.com/watch?v=gVqGCqKVM08>" %}
Get an overview of Substreams
{% endembed %}