Progressive web apps (PWAs) are web applications that have responsive designs, work offline, and can be installed on home screens. PWAs have key features like being responsive across devices, working offline through service workers, being discoverable through web app manifests, always being up-to-date, and allowing push notifications and app-like interactions. PWAs provide a faster web experience for customers compared to regular websites, improving conversion rates and revenue. They allow reaching customers who may not install a native mobile app.