Definition - What does XML User Interface Language (XUL) mean?
XUL is a user-interface language developed by Mozilla that enables developers to design cross-platform applications that can run in both online and offline modes. It is customizable using different graphics, text and layouts to support localized and internationalized markets.
Techopedia explains XML User Interface Language (XUL)
Components of XUL documents include:
Content: The arrangement of UI components is defined in the documents that together constitute the contents of XUL files.
Skin: Skin is regarded as the customizable set of colors or patterns that can be associated with a given XUL user interface defined in the form of skin files. It may include CSS and image files.