Tagging is Dartfish's notational analysis tool. It is used to identify and describe the highlights, or useful bits, in videos. This process makes it much more efficient to review, present and share those highlights. As a notational analysis tool, Dartfish is also used to derive frequency statistics for a match. The following video explains more:

Your questions answered

Is tagging just for team sports like soccer?

No, tagging lets you index any video clip, allowing you to recall events and create statistics for those events.  So it is suitable for any sport or situation for which this is useful:  Individual contests like tennis use tagging as do routine based sports like gymnastics and other traditional users of notational analysis like behavioral analysts.

I can't see the Tagging button on my Dartfish toolbar

Tagging can only be found in the TeamPro, TeamPro Data, Video Replay and Connect Plus editions of Dartfish.