AngularJS is a structural framework for building dynamic single-page web applications. It was developed by Google to overcome limitations of HTML for building interactive web apps. Some key advantages include dependency injection, data binding, and directives that automate code and simplify development. While useful for many applications, it also has some disadvantages like potential memory leaks and lack of support for older browsers. Overall, AngularJS can significantly reduce development time and costs for building complex web applications.