While Single Page Apps (SPAs) have already meant a giant leap forward, PWAs are taking things even one step further. They offer a rich user experience that parallels what users know and expect from native apps and combine that with the benefits that browser based applications provide.
This is an excellent overview using a real-world example app (that provides air quality data for locations around the world.) The app is also open source, if you'd prefer to dive right in to the code. 🏊♀️