There are over 175 Million professionals on LinkedIn. I have to admit that this is a network that I have largely ignored. When I joined it in July 2005 it was just beginning to become popular. I am going to enjoy exploring this more.
What Is It?
LinkedIn boasts itself as the World's Largest Professional Organization. This is 'probably' true since the connections there are usually business related. The ability to recommend and endorse others are a big part of this community.