Tagging is a key feature of Digital Asset Management (DAM) systems. In fact it's arguably the most crucial feature of a DAM. It's what separates a DAM from other file management systems. The ability to tag digital assets, not only makes them easier to organize and search, but also provides valuable context.
Tagging a creative asset such as an image, video or audio file simply means you're adding descriptive labels or keywords to it so that it's easier to find and use later. Tagging has never been a bad idea, but it's even more useful today as the volume of our digital assets grows exponentially. Every year we manage to create more than the last, so our total bank of assets is continually compounding. And that's OK if they're tagged properly so you can find them. If not, you end up with a Russian doll of share drive dumpster fires. Unable to find assets you know to exist, or taking 5x the hours to find them.