The UI-Router is a routing framework for AngularJS built by the AngularUI team. Unlike ngRoute, it
changes your angular app views based on state of the app and not based on the route URL (ngRoute).
The ui-router helps you to create nested views, use multiple views on the same page, have multiple views that
control a single view, and more.
To use it you need to include reference of ui-router.js file into your angular app.