For the first time over a billion people used Facebook on a single day, according to company founder Mark Zuckerberg.
The "milestone" was reached on Monday, when "1 in 7 people on Earth used Facebook to connect with their friends and family", he said in a post.
Facebook has nearly 1.5 billion users who log in at least once a month, but this was the most in a single day.
The company gained its billionth user in October 2012.
It was founded in 2004 by Mr Zuckerberg while he was a Harvard student.
In his post on Thursday, he predicted that Facebook's reach would continue to grow.