With the activity feed in each project (an exclusive feature for organizations), you can keep tabs on who's working in the project and what kind of changes they're making. When multiple people are working inside a project, activity feeds are great for keeping everyone organized and giving help where it's most needed.
To open up the activity feed pane, open up any project, then open the project settings menu (click the menu icon in the upper left of the screen).
Click on "Activity" in the sidebar to see all kinds of project changes—adding new elements, editing profiles, updating views, creating new maps, etc. It will also show you who made those edits and when.
Activity feeds are an exclusive feature for organizations.