The Site Engagement Service provides information about how engaged a user is with a site. The primary signal is the amount of active time the user spends on the site but various other signals may be incorporated (e.g whether a site is added to the homescreen).
What is a site?
Site is an inexact term. For the purposes of site engagement, we’ll be treating origins as sites.
What is engagement?
Engagement is an even more nebulous term. We want to track that the user is giving some amount of active attention to the site. To approximate this, we register a user as active when the user scrolls, clicks or types on the page. Media playback also provides a small engagement increase.
The engagement score has the following properties:
The current activity based signals are:
The current grant based signals are:
The user engagement score are not synced, so decisions made on a given device are made based on the users’ activity on that device alone.
Usage of the engagement score
Site Engagement clients should consider how their use case relates to engagement. We expect that many clients should only be using engagement as one facet of a more tailored heuristic. The engagement score has been designed with these use cases in mind:
When in incognito mode, site engagement will be copied from the original profile and then allowed to decay and grow independently. There will be no information flow from the incognito profile back to the original profile. Incognito information is deleted when the browser is shut down.
Engagement scores are cleared with browsing history. Origins are deleted when the history service deletes URLs and subsequently reports zero URLs belonging to that origin are left in history.
URLs are cleared when scores decay to zero.