Gatsby has a rich ecosystem of drop-in functionality, from CMS integrations to image optimizations.
This section has three parts. First, it covers how to use plugins, which is by far the most common use case. Second, it has documentation on themes, which enable you to modularize and re-use site sections between multiple sites. Third, it provides guides for creating and contributing a plugin to the ecosystem.
Like other Node packages, you can install Gatsby plugins using npm or yarn. Then, add it to your `gatsby-config.js` along with values for any options it takes.
Want to add a theme to an existing Gatsby site? No problem! Themes can be installed and configured like other plugins.
There are currently over 500 source plugins -- basically, integrations between third-party sources (like CMSs) and Gatsby. If you need to integrate with a data source that isn't covered, or improve an existing integration, this guide will help.