What is Timeline?

All the Members of a desktop can view Timeline for the desktop they are part of.

Timeline is a display of a list of events such as add/remove apps, links, users, etc. in chronological order.
You can access Timeline from any Desktop you are part of by clicking the corresponding button upper right.
Also for a quick search by categories of events, you can use a search filter:
Besides that, you can use keywords for better search.
More than that, you  can check all events through the calendar view