Backbone simplifies the process of creating rich browser-based apps and works seamlessly with REST APIs, but it has no support for rendering your views. Knockout has incredible data-binding and rendering capabilities for keeping your views in sync with complex data structures, but you are left responsible for the structure and implementation of the rest of your app.
If only you could use Backbone and Knockout together, developing client-side applications would be a breeze....
This is exactly what Knockback provides for you. Now you can work with your Backbone models as you normally would, and Knockback handles informing Knockout of the changes so your views are automatically (re)rendered. Never again will you have to write a tedious and error-prone render method in your Backbone view.