So, August 21, 2015 was a landmark day for Facebook:
One billion people used Facebook on Monday
During just a single day, roughly one out of every seven people on Earth logged in to the social network, says Facebook CEO Mark Zuckerberg.
“Facebook has reached a new milestone: 1 billion people using the social network in a single day.
Facebook reached the high mark on Monday, CEO Mark Zuckerberg wrote in a Facebook post on Thursday. That means roughly “1 in 7 people on Earth used Facebook to connect with their friends and family” in a single day, he added.”