Most JavaScript libraries offer a library of client-side widgets that mimic the behavior of familiar desktop interfaces. Sliders, menu bars, file list views, and more can be built with a combination of JavaScript, CSS, and HTML. Since the HTML4 specification doesn't provide built-in tags that semantically describe these kinds of widgets, developers typically resort to using generic elements such as  and . While this results in a widget that looks like its desktop counterpart, there usually isn't enough semantic information in the markup to be usable by an assistive technology.