TECHFacebook’s 12th anniversaryFacebook CEO and cofounder Mark Zuckerberg takes a selfie at Facebook headquarters in Menlo Park, CA.Martin E. Klimek, USA TODAYFacebook CEO and cofounder Mark Zuckerberg.Martin E. Klimek, USA TODAYCEO and cofounder Mark Zuckerberg.Martin E. Klimek, USA TODAYFacebook CEO and cofounder Mark Zuckerberg.Martin E. Klimek, USA TODAYFacebook COO Sheryl Sandberg at Facebook in Menlo Park, CA.Martin E. Klimek, USA TODAYFacebook COO Sheryl Sandberg at Facebook in Menlo Park, CA.Martin E. Klimek, USA TODAYFacebook COO Sheryl Sandberg at Facebook in Menlo Park, CA.Martin E. Klimek, USA TODAYFacebook COO Sheryl Sandberg at Facebook in Menlo Park, CA.Martin E. Klimek, USA TODAYCEO and cofounder Mark Zuckerberg greets visitor Raman Gulati and his three month old daughter Sohana.Martin E. Klimek, USA TODAYLaneyse Hooks hugs a another participant at the Facebook Friends day.Martin E. Klimek, USA TODAYFacebook CEO and cofounder Mark Zuckerberg at Facebook headquarters in Menlo Park, CA.Martin E. Klimek, USA TODAYFacebook CEO and cofounder Mark Zuckerberg at Facebook headquarters in Menlo Park, CA.Martin E. Klimek, USA TODAYFacebook CEO and cofounder Mark Zuckerberg at Facebook headquarters in Menlo Park, CA.Martin E. Klimek, USA TODAY