What are PWAs and how they work?

Nowadays there is an app to do almost anything: there is an app for photos and videos, an app to watch movies in streaming, an app to book airplanes and travel etc … To tell the truth there are hundreds of apps to do each of these things and browsing through the Google app stores, Apple can choose the most suitable mobile applications for our needs. However, all this may soon change. Or rather, evolve: the PWAs, Progressive Web App, are beginning to spread. That is the apps of the future, which thanks to their features offer the user a better user experience than today’s apps. But what are Progressive Web Apps and how do they work?