Facebook has been spreading across the planet over the last decade like a particularly infectious disease, infecting both young and old alike.

As of the end of June, the social network boasted a monthly active user base of over 1.49 billion people, and Facebook topped yet another milestone on Monday when it was used by over 1 billion people in a single day. For reference, the total world population is estimated to be a around 7.3 billion people, meaning that on Monday, roughly 1 in 7 people alive today were using Facebook at some point.

“When we talk about our financials, we use average numbers, but this is different,” Facebook CEO Mark Zuckerberg wrote in a post on Facebook. “This was the first time we reached this milestone, and it’s just the beginning of connecting the whole world.”

He added, “I’m so proud of our community for the progress we’ve made. Our community stands for giving every person a voice, for promoting understanding and for including everyone in the opportunities of our modern world.”

“A more open and connected world is a better world”

When you have a company with such a staggeringly high number of users, growth starts to become something of a challenge. The social network’s user base is rapidly eating up the actual internet-using market, which according to Facebook’s own report earlier this year is about 37.9 percent of the world’s population. If you do the math, that means that of the more than 2.6 billion people who have access to the internet, over a third used Facebook on Monday.

To continue growing that ridiculously large user base, Facebook will need more people using the internet in general, which could be one explanation behind the social network’s push for more widespread internet connectivity through its Internet.org program, as well as its research into high-altitude drones that beam internet access to the ground.

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

Photo by Robert Scoble