Dijit is a widget system layered on top of dojo.  If you are new to the whole Dojo experience, Dijit is a good place to start.  You can build amazing Web 2.0 GUI's using very little, or no, JavaScript. 

You can use Dijit in one of two ways: declaratively by using special attributes inside of regular HTML tags, and programmatically through JavaScript. You have the same options either way. As we did in Part 1, we'll use declarative Dijit for all the examples in this part. Part 3 will show how to make the same calls programmatically.

Dijit comes bundled with its own theme, tundra, which brings a common design and color scheme to all the widgets.  You can override the theme by container or by element to add nuance and flair. 

Everything in Dijit is designed to be globally accessible -- to accommodate users with different languages and cultures as well as those with different abilities. Language translations, bi-directional text, and cultural representation of things like numbers and dates are all encapsulated within the widgets. Server interactions are done in a way that makes no assumptions about local conventions. All widgets are keyboard accessible and using the standard Dijit theme, usable in high-contrast mode as well as by screen readers. These features are baked in so that, as much as possible, all users are treated equally.