Sometimes in May last year, Android instant app was announced at Google I/O as a feature that lets users access and run apps from search, social media, messaging, and other deep links without initially installing the app.

The good news is that Instant Apps are finally cripping into the Google Play store listings, and with just a "Try It Now button," you can access the feature. Instant Apps launch with just a tap on a URL. To support this, developers partition their apps into small, runnable parts, so they can start within seconds.

source: http://www.techpaded.com.ng/2017/10/you-can-now-test-android-apps-before.html