Progressive Web Apps (PWAs) combine the best of web and mobile applications to provide a reliable, fast, and engaging user experience.Key Features of PWAs include responsive design, offline support, installability, push notifications, security, and fast loading.Building a PWA offers benefits such as improved user experience, increased conversions and retention rates, lower development costs, and wider reach.To build a PWA, you need a secure connection (HTTPS), a Web App Manifest file, and a Service Worker to handle caching and offline functionality.