# Create an extension
URL: https://docs.awellhealth.com/docs/extensions/create-an-extension

> For the complete documentation index, see [llms.txt](https://docs.awellhealth.com/llms.txt).



An extension is a folder with a required shape, and the extensions server picks it up once the shape is
right.

## What the folder must contain [#what-the-folder-must-contain]

### Folder name [#folder-name]

The folder name identifies the extension, so choose it deliberately.

### README [#readme]

Every extension needs a README. For a public extension it becomes the extension's
[Marketplace](/docs/marketplace) page, read by people deciding whether to use the extension.

Write it for them rather than as internal documentation: what the extension does, what it needs
configured, and what its actions are.

### Changelog [#changelog]

Every extension needs a changelog. See [Versioning](/docs/extensions/versioning).

## What the extension declares [#what-the-extension-declares]

The extension declares its own metadata, its [settings](/docs/extensions/extension-settings), and the
[actions](/docs/extensions/create-an-action) it exposes.

## Start from the hello-world extension [#start-from-the-hello-world-extension]

The repository includes a hello-world extension. Read it before writing a new one; it's faster than
working out the shape from documentation.

## Next steps [#next-steps]

**Next:** [Extension settings](/docs/extensions/extension-settings), which is what the person installing
the extension fills in.