AngularJS has gained popularity due to its ability to extend HTML with additional attributes, making it easier to create dynamic and responsive web applications. Its key features include two-way data binding, dependency injection, and a modular approach, which simplifies development and testing. AngularJS supports Single Page Applications (SPA) and is maintained by Google, ensuring continuous improvements and stability. Its use in large-scale projects by companies like Netflix and PayPal highlights its reliability and effectiveness.