# Introduction

A Rancher Extension is a packaged Vue library that provides a set of functionality to extend and enhance the Rancher UI.

Developers can author, release and maintain extensions independently of Rancher itself.

Rancher defines a number of extension points - the [**Extensions API**](./api/overview.md) - which developers can take advantage of, to provide extra functionality, for example:

- Add new UI screens to the top-level side navigation - [**Top-level product**](./usecases/top-level-product.md)
- Add new UI screens to the cluster-level side navigation - [**Cluster-level product**](./usecases/cluster-level-product.md)
- Add new UI screens to the navigation of the Cluster Explorer UI 
- Add new UI for Kubernetes CRDs 
- Extend existing views in Rancher Manager by adding panels, tabs and actions 
- Customize the landing page 

> Note: More extension points will be added over time

Once an extension has been authored, it can be packaged up into a Helm chart, added to a Helm repository and then easily installed into a running Rancher system.