The definition of "Progressive Web Apps" according to Google is on https://developers.google.com/web/progressive-web-apps/ and https://codelabs.developers.google.com/codelabs/your-first-p...:

"A Progressive Web Apps is:

* Progressive - Works for every user, regardless of browser choice because it's built with progressive enhancement as a core tenet.

* Responsive - Fits any form factor: desktop, mobile, tablet, or whatever is next.

* Connectivity independent - Enhanced with service workers to work offline or on low-quality networks.

* App-like - Feels like an app to the user with app-style interactions and navigation because it's built on the app shell model.

* Fresh - Always up-to-date thanks to the service worker update process.

* Safe - Served via HTTPS to prevent snooping and to ensure content hasn't been tampered with.

* Discoverable - Is identifiable as an "application" thanks to W3C manifest and service worker registration scope, allowing search engines to find it.

* Re-engageable - Makes re-engagement easy through features like push notifications.

* Installable - Allows users to "keep" apps they find most useful on their home screen without the hassle of an app store.

* Linkable - Easily share via URL, does not require complex installation."

Generally, a "progressive web app" is something that behaves a bit like a regular native app, when the browser supports it and user allows it. This includes using serviceworkers to cache data for offline (and low bandwidth) use, making a home-screen icon that launches a standalone (from the task switcher perspective) window with no browser frame, and so on.

Pretty much what I thought, thanks!

I'm a fan of the concept, hating apps that could easily have been webpages (public transport apps are often a good example), so it sounds like a good idea to give this a name and promote it. It's too bad that this name sounds like Microsoft came up with it in the early 2000s, but oh well.

It's an awesome idea and one that is actually not too hard to implement, at least partially. Problem is browser support of the APIs, with Safari lagging behind.

Yah, the tricky bit is safari access. I'd love to put a bunch of time into using service workers, push notifications, and so on to make an app-like experience for my users (it's a forum / social network thingy for teachers), but mobile safari really puts a crimp in those plans. Instead I have my own homegrown cache and other hairy tricks that are nonstandard, but work on safari.

It's a laundry list of enhancements that are usually not in any way critical to business and product requirements, and whose absence will likely not be noticed by many users. Great to have and I support the idea 100%, but this stuff is usually the first to get cut when launch is looming, and for good reason.

According to google a progressive web app is a website that progressively becomes an app the more you interact with it.

So I guess at first visit you get things like service workers and notifications. Then after like 5 or so visits you get to install it to the home screen and the address bar optionally gets hidden or played around with or something.

It used to be 2 visits in 5 min (assuming web manifest, https and service workers are enabled).

But, I guess, these things are subject to change.