A Progressive Web App isn’t one type of thing or even a thing. It’s more a commitment to making your website as speedy and responsive as possible. And guidelines for creating a modern pile of JavaScript, CSS, and HTML that behaves well on both mobile and desktop browsers.

Proponents like Google have created documentation explaining just what they think it means to be progressive and you can use their vision as a starting point. There are a dozen or so strategies behind the code for a good web app. You’ll want to start with a small, clean framework that pops up quickly. The rest of the data can be added from background services later.

You might also make sure that common data types are marked up with special tags to help search engines find them. (Remember that Google is in the search engine business.) Products from catalogs, for instance, should come with extra tags that indicate the price, the description, and the image, all to make sure that scraping apps don’t get lost.

You can even audit your web app’s progressiveness. Google’s Chrome includes a special tab in the Developer Tools window that checks a site for many of the common requirements. You don’t need to hit everything on the list, but the more you get the better the experience will be for anyone who visits.

— Peter Wayner