AngularJS is a toolset for building the framework most suited to your application development.It is fully extensible and works well with other libraries. Every feature can be modified or replaced to suit your unique development workflow and feature needs.
HTML is great for declaring static documents, but it fails when we try to use it for declaring dynamic views in web-applications or web documents. AngularJS lets you extend HTML vocabulary for your application. The resulting environment is extraordinarily expressive, readable, and quick to develop.
AngularJS has several advantages in web development.
AngularJS combines the functionalities of most of the 3rd party libraries, it supports individual functionalities required to develop HTML5 Apps. While Backbone.js do their jobs individually.
You will be able analyze, solve and implement real world problems all by yourself.Also you will be able to create responsive web documents.
Large organisations like Google, Yahoo, Microsoft, GitHub, Mozilla etc.. have started using AngularJS .