What is "Progressive Enhancement"?

There's this other core concept I want to emphasize as well, it's a progressive web app, what does the progressive actually mean? It doesn't mean you can use the device camera. Indeed, it basically means that we can progressively enhance our web application. So let's consider this starting point, we have three different web apps, one is a legacy web app, so an older web app using older technology and probably also supporting older browsers. Then we have an existing modern app which is maybe also a traditional web app, not not a single page application nothing fancy but it target's modern browsers because maybe it's an internal company tool or some page which mainly addresses tech enthusiasts, something like that and maybe we have an upcoming project and there, we can pretty much bank on people having more modern browsers because support is already getting better, more people are using modern browsers, it's probably going to be better in the future too. So we have these three different apps, can we only turn the upcoming project into a progressive web app now? Because rewriting an existing app from scratch certainly isn't an option, so if you want to turn this into a progressive web app, you can't just start over. Well let's have a look at the near future, we can simply add some features to our existing app and this is actually something I will show you on the course. We will take a project and add features step-by-step and you can stop at any given point, you can stop after adding an app manifest and a basic service worker. You can stop after you implement the basic caching, advanced caching, push notifications, you can stop all the time. Now your existing modern app, here you can maybe implement some more progressive web app features and for the upcoming project you have there, you can start from scratch obviously, so you can fully implement it as a progressive web app right from the start and plan everything with that in mind. Now in the further away future, our older application might use some or multiple progressive web app features but not all of them and that's perfectly fine, you don't have to use zero or 100% percent, you can absolutely use 40% of all the features you learn in the course, pick the ones which enhance your application and add them. Now therefore our middle app here maybe is a completely converted progressive web app in the end because we added all the features which make up a progressive web app. We have solid caching in different circumstances, we use push notifications and all that stuff. And our upcoming project already of course was planned as a progressive web app and therefore also is one and this is important because I know that a lot of people are looking at all these technologies and are saying, well I don't have the resources or the time to rebuild my old app and I have to support old browsers anyways, these users are never going to see the new features and I can only answer you, that's not a problem, simply add the features which enhance your application right now and feel free to turn it into a complete progressive web app if you have the time. Definitely consider it for all upcoming projects though.