Instant Apps were first announced over a year ago at Google I/O 2016. Put simply, when tapping on search results from a supported site, a minimal version of the site's app would quickly install and immediately display the content. For example, tapping on a Vimeo link would open the Vimeo app and the video would start playing.
The feature started gradually rolling out in January, and became open to all developers in July. Google has continued to roll out the feature over the past few months, and the company now says that 500 million Android devices have Instant Apps enabled. Instant Apps are currently compatible with Android 6.0 and up (with support for 5.0+ planned), but not every Android 6.0+ device has the feature enabled.
Google also pointed out that developers are seeing increased user engagement and acquisition as a result of creating Instant Apps. For example, average session duration on Vimeo has increased by 130%, customer conversion rates on Jet (a shopping platform) increased by 27%, and New York Times Crosswords showed twice the number of sessions per user.
By sharing these stats, Google is trying to encourage more developers to add Instant App compatibility to their existing applications. After all, 500 million potential users for your site/product and potentially higher engagement is certainly tempting.
- Android Developers