Social media is person-to-person, person-to-many and many-to-many, with technology where all those hyphens are. Sites like Facebook, Twitter, Wikipedia, Digg, YouTube, Yahoo! Answers and Second Life all fall under the heading of social media, but each falls into a different category.
1. Communication
Social networking sites, blogs and micro-blogs. Sites like Facebook, Twitter and your friend’s blog about vintage gas caps communicate ideas and inspire comments.
2. Collaboration
Social bookmarking, social news and wikis. Sites like StumbleUpon, Digg and Wikipedia let people build upon the ideas of others. Sometimes arguments break out. Collaboration isn’t always easy.
3. Multimedia
Video sharing, photo sharing and audio sharing sites. YouTube and Flickr help fill this creek. Swim around. It’s deep and wide.
4. Reviews and Opinions
Question & Answer and product review sites. Yahoo! Answers, WkiAnswers and epinions have large, and vocal, followings. Very useful for getting or giving the skinny about something.
5. Entertainment
Virtual worlds and game sharing. Second Life and Kongregate are two of its leaders. Careful. Some people never come back.



