Progressive Web Applications (PWAs) are web apps that deliver a native-like experience on browsers and mobile devices. They combine the best of web and mobile applications, offering offline access, push notifications, and fast performance. PWAs are built using standard web technologies like HTML, CSS, and JavaScript and are installable on user devices without app stores. They are cost-effective to develop and maintain, making them an attractive option for businesses looking to improve user experience. PWAs help bridge the gap between web and mobile app ecosystems.