# CXR Overview

### Introduction

The Customer Experience Runtime (CXR for short) is a versioned runtime where your Applications are run. Like Studio is where your apps are _built_, the CXR is where your apps _run_ once published.

### Versioning

Applications are deployed to the latest CXR version by default. When Airkit makes changes to the CXR, we increment either a minor or major [version change](cxr-upgrades-and-migrations). Minor version changes are often small user experience changes or bug fixes, while major version changes represent new features or functionality that was previously unavailable. Major version changes may require edits to an existing application.

### Upgrading CXR

Airkit is continually fixing bugs and adding new features to our platform. It is good practice to periodically test and if prompted, upgrade your CXR version and re-publish. [Learn more about CXR upgrades.](cxr-upgrades-and-migrations)

If you have questions about the upgrade process, please contact [support@airkit.com](mailto:support@airkit.com).
