Thing 13-Tagging

I wasn't able to totally figure out tagging. I have tagged photos before in facebook and have been tagged. However, this seems to be different. I didn't get much help from the information provided. When I completed Thing 14, I was able to tag bookmarks and I can see where that would be a tremendous help in organizing data. As far as library use, it seems that it could get cumbersome and overdone if anyone can add to anything. Maybe as I use it more, I will have a better feel for practical use in library setting.