This is the one I did a presentation about. It is about people who upload just about anything onto the internet, videos, pictures, Blogs, bookmarks, ect, and then tag them so others can find them. Tagging is simply giving them a few key words so when people search these words then what ever is tagged with them will show up.
There are numerous sites made for tagging and thereby sharing. Sites like fliker for pictures, or delicious for bookmarks, it’s amazing the amount of content people will put up just to share. You'd hope they could just do it in real life but since virtual items have no giant value attached to them they can be free. Some site incorporate their own tagging features like facebook which has its own tagging in pictures. One thing about tagging is that it can be a little dangerous. Like everything else on the Internet, once it’s up its public. You might accidentally put up something you didn’t mean to or someone can steal something you put up and claim it as their own.