This page will not display anything unless you select a tag in the filter menu. It’s created like this because the page is best used with a very small selection of tags. Showing the data of too many tags would make the page unusable.
After selecting a tag you will see it’s activity in the Aggregated tag activity widget:
You will see how active the tag was (= how fast it was moving) and in which zones it has been (= shown by the background color).
Looking at the example above we can see that the tag we have selected (tag 0) has been moving back and forth between the Hardware lab and Calling cell 1. Hovering over a point in time on the Aggregated tag activity widget will show the position of the tag at the same point in time on the Trajectories widget: At 15:53 tag 0 was in the Hardware lab. We can see this on both the Aggregated tag activity widget and on the Trajectories widget.
You can zoom in and out in time by scrolling on the Aggregated tag activity widget. You can also click, hold, drag and release on it to zoom in on a certain time period.