The .appx file extension is used for application packages in the Universal Windows Platform (UWP). It's essentially a ZIP archive that contains all the files needed to install and run a UWP application on Windows 8, Windows 8.1, Windows 10, Windows 11, and Xbox. This includes executable code (.exe or .dll files), resources (images, audio, video), metadata (application manifest), and other necessary components. The application manifest, typically named AppxManifest.xml, is a crucial file that describes the application, its dependencies, required capabilities (like access to the camera or microphone), and other essential information for the operating system to properly install and manage the application. The .appx format provides a standardized way to distribute and install UWP applications, ensuring consistency and security across different Windows devices. It also supports features like automatic updates and sideloading (installing apps from sources other than the Microsoft Store). The .appx format replaced the older .appxupload format for submitting apps to the Microsoft Store. The .appx package is digitally signed to verify the publisher's identity and ensure the integrity of the application, preventing tampering or malicious modifications.