The Timeline feature, which is the desktop PC version of the broader feature set that Microsoft officials have dubbed "Pick Up Where You Left Off," was one of the new Fall Creators Update features Microsoft highlighted at its Build 2017 developers conference earlier this year.
Microsoft's broader plan is to allow activities created on one device to be moved to other Windows and non-Windows devices using Cortana and the cloud using the broader Pick Up Where You Left Off technology that comes from Microsoft's "Project Rome" work.
Under the covers, Timeline and Pick Up Where You Left off use the Microsoft Graph and Activity Graph to provide users with these new experiences.
The Windows 10 Cloud Clipboard shown at Build 2017 isn't there yet, nor is the Capture 3D app that Microsoft showed off in October 2016 and which was expected to be in the original Creators Update release. New Continuum features for Windows Phones, described by Microsoft officials last year and which some expected to be part of the Creators Update, also have yet to materialize.