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## Resource: About Data Collections

## Article: About Data Collections

## Article Link: https://dev.wix.com/docs/backend-extensions/data-collections/about-data-collections.md

## Article Content:

# About Data Collections

A [data collections](https://dev.wix.com/docs/overview/extensions-framework/backend-extensions/data-collections.md) extension declares CMS collections that Wix creates on a site when an app or a headless project is installed there. This reference is the shared contract for that extension. It covers the generated files, the builder that registers the collections, and the definition of each collection.

A Wix CLI app and a Wix-managed headless project each generate a builder file and one definition file per collection. Both import the builder from `@wix/astro/builders`. Self-managed apps define the same collections as JSON in the app dashboard instead of these files. See [Add a Data Collections Extension in the App Dashboard](https://dev.wix.com/docs/build-apps/develop-your-app/extensions/backend-extensions/data-collections/add-a-data-collections-extension-in-the-app-dashboard.md).

A Studio Two site doesn't use this extension. A site creates collections directly. See [Create a Collection](https://dev.wix.com/docs/studio-two/code-your-site/work-with-data/introduction/create-a-collection.md).

## What's in this reference

- [Data Collections Extension Files and Code](https://dev.wix.com/docs/backend-extensions/data-collections/data-collections-extension-files-and-code.md): The generated file set, the `extensions.dataCollections()` builder fields, and the fields of each collection definition.

The [Data Collections Extension JSON Reference](https://dev.wix.com/docs/api-reference/business-solutions/cms/collection-management/data-collections-extension/introduction.md) is the full schema for a collection definition, including every field type, permission role, index option, and the initial data format.

## See also

- [Data Collections](https://dev.wix.com/docs/overview/extensions-framework/backend-extensions/data-collections.md)
- [Data Collections Extension Files and Code](https://dev.wix.com/docs/backend-extensions/data-collections/data-collections-extension-files-and-code.md)
- [Data Collections Extension JSON Reference](https://dev.wix.com/docs/api-reference/business-solutions/cms/collection-management/data-collections-extension/introduction.md)
- [About the Wix Data Collections API](https://dev.wix.com/docs/api-reference/business-solutions/cms/collection-management/data-collections/introduction.md)