What is XML User Interface Language (XUL)?
XUL is a user interface language developed by Mozilla that allows developers to design cross-platform applications that can run in both online and offline modes. It can be customized with various graphics, text, and layouts to support localized and internationalized markets.
Content: The arrangement of UI components is defined in the documents that together form the content of XUL files.
Skin: Skin is seen as the customizable group of colors or patterns that can be associated with a particular XUL user interface in the form of skin files. It can contain CSS and image files.