A Progressive Web App, or PWA, is a term for any web application that uses modern web technologies and design patterns to provide a reliable, fast, and engaging user experience.

The following features define a basic PWA website:

• Fast - PWA sites use a variety of performance optimization strategies to provide a responsive experience or load content fast, even on slow networks.
• Secure - PWA sites use HTTPS connections for enhanced security.
• Responsive - PWA sites implement responsive design strategies to provide a consistent experience on desktops, tablets, and mobile devices.
• Cross-browser compatible - PWA sites work equally well on all modern browsers, such as Chrome, Edge, Firefox, Safari.
• Offline Mode - PWA sites cache content to ensure that some content can be served when a user is offline.
• Mobile "Install" - Mobile users can add PWA sites to their home screens and even receive Push notifications from the site.
• Shareable content - Each page in a PWA site has a unique URL that can be shared with other apps or social media.

The RAIL model lays out the user-centric goals for PWA websites:

• Response – An application is receptive to the user's request.
• Animation – It shows a movement to keep the user pausing.
• Idle – A PWA utilizes the "idle" second to cache content.
• Load – It loads under a moment.