# App

> Source: https://agilitycms.com/docs/overview/glossary-app

An **App** is a self-contained micro-site that is installed into an Agility instance to extend the Content Manager. An App can provide visual functionality, connect to external systems and do background processing. For example, an App can add a custom field that connects your Agility content to an external service by ID.

Marketplace Apps are tested, curated and available to all Agility customers. Private Apps have the same capabilities but are built with the Apps SDK, hosted by you, and registered within your organization, so they appear only in its instances.

**Also called:** Agility App, Custom App. Older articles describe Custom Apps as providing Custom Fields only.

## Related terms

- [Custom Field](/docs/overview/glossary-custom-field)
- [Organization](/docs/overview/glossary-organization)
- [Instance](/docs/overview/glossary-instance)

## Learn more

- [App Types In Agility](/docs/apps/apps-in-agility)
- [Creating Apps for Agility](/docs/apps/creating-apps-for-agility)
- [Apps SDK](/docs/apps/apps-sdk)
- [Apps (Developer)](/docs/developers/apps)

[All glossary terms](/docs/overview/glossary)

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## Related pages

- [Agility Glossary](https://agilitycms.com/docs/overview/glossary.md)
- [Asset](https://agilitycms.com/docs/overview/glossary-asset.md)
- [Batch](https://agilitycms.com/docs/overview/glossary-batch.md)
- [Channel](https://agilitycms.com/docs/overview/glossary-channel.md)
- [Component](https://agilitycms.com/docs/overview/glossary-component.md)
- [Component Model](https://agilitycms.com/docs/overview/glossary-component-model.md)
- [Content List](https://agilitycms.com/docs/overview/glossary-content-list.md)
- [Content Model](https://agilitycms.com/docs/overview/glossary-content-model.md)
- [Content Sync](https://agilitycms.com/docs/overview/glossary-content-sync.md)
- [Custom Field](https://agilitycms.com/docs/overview/glossary-custom-field.md)
- [Dynamic Page](https://agilitycms.com/docs/overview/glossary-dynamic-page.md)
- [Fetch API](https://agilitycms.com/docs/overview/glossary-fetch-api.md)
- [Fetch Key](https://agilitycms.com/docs/overview/glossary-fetch-key.md)
- [Gallery](https://agilitycms.com/docs/overview/glossary-gallery.md)
- [GraphQL API](https://agilitycms.com/docs/overview/glossary-graphql-api.md)
- [Instance](https://agilitycms.com/docs/overview/glossary-instance.md)
- [Knowledgebase MCP Server](https://agilitycms.com/docs/overview/glossary-knowledgebase-mcp-server.md)
- [Linked Content](https://agilitycms.com/docs/overview/glossary-linked-content.md)
- [llms.txt and Markdown Twins](https://agilitycms.com/docs/overview/glossary-llms-txt.md)
- [Locale](https://agilitycms.com/docs/overview/glossary-locale.md)
- [Management API](https://agilitycms.com/docs/overview/glossary-management-api.md)
- [MCP Server](https://agilitycms.com/docs/overview/glossary-mcp-server.md)
- [Nested Content](https://agilitycms.com/docs/overview/glossary-nested-content.md)
- [Organization](https://agilitycms.com/docs/overview/glossary-organization.md)
- [Page](https://agilitycms.com/docs/overview/glossary-page.md)
- [Page Model](https://agilitycms.com/docs/overview/glossary-page-model.md)
- [Personal Access Token](https://agilitycms.com/docs/overview/glossary-personal-access-token.md)
- [Preview Key](https://agilitycms.com/docs/overview/glossary-preview-key.md)
- [Shared Content](https://agilitycms.com/docs/overview/glossary-shared-content.md)
- [Sitemap](https://agilitycms.com/docs/overview/glossary-sitemap.md)
- [Staging and Published](https://agilitycms.com/docs/overview/glossary-staging-and-published.md)
- [Web Studio](https://agilitycms.com/docs/overview/glossary-web-studio.md)
- [Webhook](https://agilitycms.com/docs/overview/glossary-webhook.md)
- [Workflow](https://agilitycms.com/docs/overview/glossary-workflow.md)
- [Zone](https://agilitycms.com/docs/overview/glossary-zone.md)

Index of every docs page: https://agilitycms.com/docs/llms.txt