The world has 7 billion people and of those 1 billion people used Facebook on a single day on 27 August 2015. It is an estimate of the popularity of Facebook which is touching the lives of billions of people, and for those people who believe its getting over for Facebook, it is an eyeopener!
Mark Zuckerburg, Founder and CEO of Facebook, announced this huge milestone on Facebook by saying that 1 in 7 people on Earth used Facebook to connect with their friends and family on that day.
Facebook even posted a celebration video to mark the event
https://youtu.be/efXC4V6melk
Well the growing popularity is also reflected in the Facebook stock price as it continues to rise year after year and is seems to be loved by share holders on NASDAQ.