AppImages like Snap/Flatpack applications are self contained programs that do not require additional libraries and files to be installed. All requirements are packed into one single file to download. Normally you would have to download the file set it’s permissions to executable and run the file.
Enter AppImages Launcher this little app makes managing AppImages a breeze from the desktop. Simple Download your chosen app. Open it from your file manager and AppImageLauncher does the rest integrating it into your system and placing an icon in the desktop menu.
Want to update or uninstall is easy just right click on the launcher and your given the following dialog.
Binaries are available in RPM and .deb format but if your using Ubuntu 18.04 make sure you download the .deb file marked with bionic. Ironically it can also be installed as an AppImage file and are available here
You can find a list of applications at the AppImage Hub here