1 billion people logged into Facebook on Monday

It was a special day ... for Facebook

Facebook reached a massive milestone this week, with Mark Zuckerberg announcing that a billion people logged onto the social networking site on Monday.

That's means one out of seven people on Earth used Facebook on a single day.

"This was the first time we reached this milestone, and it's just the beginning of connecting the whole world," Zuckeberg wrote in a post today.

This is especially impressive as there was no special event or holiday that might have pushed users to log in on Monday - there was just a lot of people using Facebook.

Connecting the world

Facebook received a lot of major updates this year, including a bigger push into videos, as well as live streaming.

Facebook has also been pushing for a more connected world for a while now, with the company working on projects that include Internet.org, as well as a giant solar-powered plane built to deliver internet to remote areas of the world.

"A more open and connected world is a better world. It brings stronger relationships with those you love, a stronger economy with more opportunities, and a stronger society that reflects all of our values," Zuckerberg added in his post.

"Thank you for being part of our community and for everything you've done to help us reach this milestone. I'm looking forward to seeing what we accomplish together."