Engaged time
Engaged time is the time a visitor spent actively using a page: the tab in the foreground, and the visitor scrolling, clicking, typing or moving the pointer. It stops when the tab is hidden, and 10 seconds after the visitor last did something when the page is left untouched. It starts again when they come back.
The Silktide Script measures it for each page view and adds it up across the visit. That total is the visit's : Analytics reports duration as engaged time, not as the time a page was open. The walkthrough of a visit on the Journeys screen shows it for each page, beside the time between arriving on the page and leaving it.
Each website has an engaged-time threshold, 10 seconds unless changed. A visit that sees one page and has less engaged time than that is a .