“Progressive web app” (PWA) is both a general term for a new philosophy toward building websites and a specific term with an established set of three explicit, testable, baseline requirements. As a general term, the PWA approach is characterized by striving to satisfy the following set of attributes:
Responsive
Connectivity independent
App-like-interactions
Fresh
Safe
Discoverable
Re-engageable
Installable
Linkable
As a specific term, websites can be tested against the following three baseline criteria to qualify as a PWA:
It must run under HTTPS.
It must include a Web App Manifest.
It must implement a service worker.
PWAs are apps delivered through the web (as opposed to native apps, which are packaged and deployed through stores). As Alex Russell, who together with Frances Berriman coined the term PWA, said:
they’re just websites that took all the right vitamins.
