A Progressive Web App is a website that appears to the user like an normal app on their phone, tablet, or computer. It looks and behaves like a normal app, but is accessed through a normal web page. This means that it works on both phones and computers, and it doesn't need to be downloaded as an app from a store like the App Store or Google Play. PWA's are faster and more reliable than a normal website, meaning they work better on slower connections and don't need a lot of data to load the pages. They also work offline and can send push notifications to remind the user to check in on the website.