How to use Angular.js? Introduction of Angularjs/ Addition in Angularjs.

AngularJS is a structural framework for dynamic web apps. It lets you use HTML as your template language and lets you extend HTML's syntax to express your application's components clearly and succinctly. AngularJS's data binding and dependency injection eliminate much of the code you would otherwise have to write.
AngularJS is used as a frontend entity for your web app.

Scope:
A controller (constructor) function is responsible for setting model properties and functions. This can be done only through $scope. Whatever function or model you apply in View (html file), that is accessed in controller using scope. Only methods defined on this $scope object are accessible from the HTML/view.