Facebook passed another milestone, reporting Wednesday that its base of monthly active users passed 1.5 billion for the first time.
Facebook crossed the 1 billion monthly user mark in September 2012, so it's taken about three years to add the last half billion.
It took just over two years to amass the half billion before that.
For comparison, Twitter has about 320 million monthly users.
The social network announced another milestone in August, when it said the number of people who accessed Facebook in a single day passed 1 billion for the first time.
"When we talk about our financials, we use average numbers, but this is different.
This was the first time we reached this milestone, and it's just the beginning of connecting the whole world," Zuckerberg said at the time.