Copied from one of my posts on the previous announcement with some tweaks: Both Ember and Backbone fall into what I call the KVO frameworks category (Angular,

Copied from one of my posts on the previous announcement with some tweaks: Both Ember and Backbone fall into what I call the KVO frameworks category (Angular, Javascript MVC, Knockout, Batman, others). Both use jQuery for DOM manipulation and revolve around the idea of having a canonical model and having that as the center of your app. As you change the model, it fires events that you use to update the DOM. The difference is that Backbone is philosophy. Backbone provides a basic but complete set of tools for observing model changes combined with a set of utilities that are useful but not prescriptive to make wiring up DOM events, URL handling, etc straightforward. It works with what's in jQuery/the browser. All together, it provides the organization most js apps are sorely lacking but doesn't dramatically reduce LoC over what you could do with well factored jQuery and underscore. It's nice enough that the YUI team basically adopted it wholesale for the App framework in 3.5. Ember is all about binding. You can not only observe properties but bind them to other properties bidirectionally so that changing one causes the change to propagate through all bound values including things like values being arrays. This extends to the Handlebars templating (which was written for Ember) where you can bidirectionally bind, for example, a boolean on your model to a checkbox and to a class on a div so that checking the checkbox toggles the class without anything in your app directly manipulating the DOM. Setting this up is just the attribute plus two object path strings in the template. This works not just between the template and model but also between model objects, for arrays of models, and for nested models and nested views. Used properly, this takes care of a significant fraction of client side state managment and a resulting reduction in LoC. The cost is that Amber is 7x the size of Backbone, the templating language is tied to the framework, and there's more overhead in understanding the concepts, how they fit together, and how to apply them to your code. When I talk to people who are writing jQuery spaghetti, I steer them towards Backbone for the simplicity and superior docs but mention that I use Ember for my own projects.