<a gi-track='captionPersonalityLinkClicked' href=/galleries/search?phrase=Mark+Zuckerberg&family=editorial&specificpeople=4841191 ng-click='$event.stopPropagation()'>Mark Zuckerberg</a>, chief executive officer and founder of Facebook Inc., introduces Graph Search at Facebook headquarters in Menlo Park, California, U.S., on Tuesday, Jan. 15, 2013. Facebook Inc. introduced a search tool for its social network of more than 1 billion users, seeking to improve features to attact more users and advertisers. Photographer: Noah Berger/Bloomberg via Getty Images