You can identify faces of people featuring in your photos and then organize photos containing them. The identified faces then populate as people stacks based on this labeling. People view allows you to organize your photos based on the people you identify in each photo.
By switching to People view, you can see stacks of all labeled people. Double click on a person's stack to view all images having that person labeled in them.
The tag panel must be activated to view the people tags. Click Tags/Info in the action bar to activate Tags panel.