An APPIMAGE file is a software package saved in the AppImage format, which is used to distribute programs for installation in various versions of Linux. It is a compressed image that includes all the libraries and dependencies required to run the program.

The AppImage format was developed to streamline the process of downloading and installing programs in various distributions of Linux, such as Ubuntu, Kubuntu, Edubuntu. APPIMAGE files are an alternative to the commonly used .DEB and .RPM software packages. Once you download an APPIMAGE file you can run the program included in the package without installing installation software, such as AppImage, or system soot access. To make the APPIMAGE executable, right-click the file, select "Properties," then click "Allow executing file as program" under the "Permissions" tab. You can also type chmod +x filename.appimage on the command line. This allows you to double-click the file to run the program similar to an .EXE file in Windows.