Before I show you how to customize jQuery Mobile pages and widgets let us first discuss what is jQuery Mobile and how it works. The standard jQuery Mobile application is built from at least one page up to any number you can think of.
The page is the primary unit of interaction in jQuery Mobile and is used to group content into logical views that can be animated in and out of view with page transitions. An HTML document may start with a single “page” and the AJAX navigation system will load additional pages on demand into the DOM as users navigate around. Alternatively, an HTML document can be built with multiple “pages” inside it and the framework will transition between these local views with no need to request content from the server.