Visitors tab: what exactly does the "Came From" column identify?

The "Came From" signifies what page the viewer used to locate your profile. Whether they searched you on Google or clicked on your "featured pro profile" from the homepage, you'll see it under this column. 

Note: Due to the number of websites and site pages on ProZ.com, there may be entries in your "Came From" column that you don't recognized or understand. However, overtime with more development and use of the function we will be able to correct that problem. Thanks for being patient.