Tag is the keyword which users add to one object
Comment is what the tagger adds to the object or tag during the tagging
Source is the place where the object is hosted. It can be delicious, flickr, youtube, etc.
Tagging can be viewed as voting. Vote can be the number of different taggers tagging a bookmark, a photo or a video as favoriate.
Date is the time stamp o fte tagging behavior. Format is "MmmYY"
Tagging is the concept which is created to link other concepts. Itself does not have any real meaning
object is the thing which tagger is tagging. It can be bookmarks, photos, videos, musics, books, slides, etc.