With Backbone, you represent your data as Models, which can be created, validated, destroyed, and saved to the server. Whenever a UI action causes an attribute of a model to change, the model triggers a “change” event; all the Views that display the model’s state can be notified of the change, so that they are able to respond accordingly, re-rendering themselves with the new information.
By writing your application with Backbone, you’re keeping your code in a clean, strict environment, using RESTful services. It also takes care of much of the boilerplate code you’d have to write for interactive apps, and provides you with a best-practice environment that will be easier for you or any collaborators to maintain.
If you’re looking for more information, a good way to familiarize yourself with Backbone is by checking out real-world examples. If you’re looking to learn how to get started, I like this tutorial by Thomas Davis.