I just checked the traffic on one of my websites and my traffic was cut in half starting February 19th. I checked Serpbook and saw that I dropped from the 1st page to like the 7th page for 15-20 major keywords around the 19th and 20th. I have not done a single ounce of link building, or anything remotely close to black hat. In fact, I haven't done anything. The site has been up for 2 years. WTF just happened?