The jQuery framework has been around for about three years now. It’s rapidly becoming the go-to JavaScript framework – it has the most plugins, serious support from the likes of Microsoft and Nokia, and it is easier to use than many other frameworks. There’s an even cooler technology out there nowadays, though – jQuery UI.

jQuery UI is a set of widgets, effects, and interactions built on top of jQuery. In order to use jQuery UI, you need to include an additional JavaScript file, and optionally a set of theme files. The big difference between jQuery and jQuery UI is that jQuery is meant to build components, and jQuery UI is a set of components that are already built.

Each jQuery widget is very flexible in it’s use. Examples of the widgets available are accordions, datepickers, tabs, dialogs, and a few more of lesser value. Widgets can easily consume jQuery effects and interactions seamlessly (and without significant cross-browser issues), allowing jQuery UI users to easily create rich client-side behavior.

In addition, perhaps the coolest feature of jQuery UI is the themeroller that it was built as a part of the total package. The themeroller allows graphic designers to generate the styling for all jQuery UI components, which in turn generates a set of CSS files that are easily downloaded as a zip package which can be consumed by developers. A huge number of styles are achievable using the tools provided, which will help jQuery UI sites from looking too cookie-cutter as the framework becomes more popular amongst web developers.