Facebook. Facebook is a mobile application and website that enables people to connect, share, discover, and communicate with each other on mobile devices and personal computers. We had 1.04 billion daily active users (DAUs) on average in December 2015, an increase of 17% compared to December 2014. We had 934 million DAUs who accessed Facebook from a mobile device on average in December 2015, an increase of 25% compared to December 2014. There are a number of different ways to engage with people on Facebook, the most important of which is News Feed which displays an algorithmically-ranked series of stories and advertisements individualized for each person.