In 2009, Microsoft, working with Dartmouth College, developed PhotoDNA, a technology that aids in finding and removing some of the “worst of the worst” images of child sexual exploitations from the Internet. Microsoft donated the PhotoDNA technology to the National Center for Missing & Exploited Children (NCMEC), who established a PhotoDNA-based program for online service providers to help disrupt the spread of child pornography online. Over the next year, Microsoft, working with NCMEC, implemented a gradual rollout of PhotoDNA on Bing, SkyDrive and Hotmail services. In early 2011, Facebook joined Microsoft in sublicensing the technology for use on its network. It is our hope that other online service providers will follow Microsoft and Facebook’s lead in adopting this game-changing technology.