AngularJS is an open-source JavaScript framework developed by Google for building single-page applications, enhancing browser-based applications with MVC architecture. Key features include two-way data binding, deep linking, and a rich set of directives, which make it easier to create dynamic user interfaces. The document outlines how to set up an AngularJS application, use its core capabilities, and manage dependencies and project structure with tools like Yeoman, Grunt, and Bower.