XULRunner is a package which can be used to run applications written in HTML or XUL. It can also be used to embed the gecko rendering engine into binary applications. XULRunner is not a product; it is a tool which can be used to create products. It is a byproduct of Firefox development and the Mozilla community does not have a strong commitment to support XULRunner development apart from Firefox development. For more information about using XULRunner or how to use this binary package, see the Mozilla Developer Center article: https://developer.mozilla.org/en/XULRunner