# Companion app

> The Home Assistant app for Android, iOS, and macOS. It shows the frontend, and adds sensors, notifications, and widgets from the device.

Source: https://contributors.home-assistant.io/glossary/companion-app/

- In code: `mobile_app`
- Also: companion apps, mobile app

The companion apps connect through the `mobile_app` integration, which turns the phone into a device with entities, like its battery level and location.

## Related terms

- [Frontend](https://contributors.home-assistant.io/glossary/frontend/): The web interface of Home Assistant, built with Lit and TypeScript, in the home-assistant/frontend repository.
- [Person](https://contributors.home-assistant.io/glossary/person/): Someone in the household, with the device trackers that tell where they are, and optionally a user account to log in with.
- [App](https://contributors.home-assistant.io/glossary/app/): Extra software that runs next to Home Assistant on Home Assistant OS, like an MQTT broker or a file editor.