XML User-interface Language. XUL is a cross-platform language for describing the user interface of applications. XUL is made up predominantly of XML documents that describe the widgets. The resulting XUL UI is commonly modified and programmed with CSS and JavaScript. XUL was developed by Mozilla, so see also the Mozilla XUL reference.
(eXtensible User-interface Language) a markup language similar to HTML and based on XML. XUL previously defined what the user interface will look like for a particular piece of software. XUL is used to define what buttons, scrollbars, text boxes, and other user-interface items will appear, but it is not used to define how those items will look (e.g. what color they are). The most widely used example of XUL use is probably in the Mozilla web browser, where the entire user interface is defined using the XUL language.
XUL (pronounced zool ), the XML User Interface Language, is an XML user interface markup language developed by the Mozilla project.