One of the more interesting features shown off at Google I/O last year was Instant Apps, a new way to run Android applications without any installation. For example, during the presentation it was shown how tapping a Buzzfeed video link would play the content in the Buzzfeed app, only downloading the parts required for video playback. Keep in mind that this is different from the streaming apps functionality Google introduced in 2015.
A Google Play Services teardown from November revealed that Instant Apps were nearing public release, and now the time has come. The first wave of Instant Apps will be available "in a limited test," including BuzzFeed, Periscope, Wish, and Viki. The functionality is available all the way back to Android Jellybean, thanks to being a component of Google Play Services.
Existing applications have to be modularized to allow running on-the-fly, for which a full SDK will be available "in the coming months." If you're a developer, you can already start taking steps for Instant Apps support. Hopefully this feature rolls out to all users very soon.
Source: Android Developers