It is a framework that is primarily used to build single-page web applications.
AngularJS supports features such as:
AngularJS extends HTML to give it native Model-View-Controller (MVC) capabilities.
It allows you to use a portion of your page as one application, rather than forcing the entire page to be an AngularJS application.
Angular is a full-featured Single Page Application framework.
The AngularJS source code is made freely under the MIT license.