Facial Recognition in Photo Sharing Sites

While researching information for another blog article, I ran across an article where Shutterfly was sued for using facial recognition in their database.  So, I had to jump on this as facial recognition and tagging are used more and more in photo sharing sites.  So what is facial recognition and tagging?  And, how does it affect you?   In order for us to learn about facial recognition, we need to take a look at tagging first.