The most-visited social media site is back in the news for a couple of reasons. Facebook released financial documents last week as it prepares for the first public sale of ownership shares. At the same time, new research suggests the site's popularity will last, rather than declining as users get bored.

Most attention is stirred by previously secret business data about the eight-year-old company's astounding size: Its 845 million global users upload 250 million photos a day and click "like" on posts about 2.7 billion times daily. Roughly 483 million users are active on the site at least once each day.

Facebook disclosed that it adds U.S. users at a slower rate than in other countries, indicating it already has attracted a high percentage of Americans interested in online networking. According to the new research study, longtime users typically don't show "Facebook fatigue." The respected Pew Research Center found no sign that veteran members get tired of posting pictures, relaying links, updating weekend plans or sharing random thoughts. Instead, the longer people have used the site, the more frequently they hit the "like" button, comment on friends' content, post status updates and tag friends in photos, shows the national survey of 2,255 adults. "For most people, the longer they are on Facebook, the more they do on Facebook,” says Keith Hampton, a Rutgers University professor who is the study's main author.

Founder says: "We often talk about inventions like the printing press and the television. Today, our society has reached another tipping point." -- Mark Zuckerberg in letter with stock filing documents

Blogger says: "Zuckerberg has created an empire that he will continue to rule. This is not necessarily a bad thing. He is young, but he has already accomplished more than most of us will in our lives. He is the guiding force behind Facebook." -- Steven Davidoff, New York Times business blogger

New study shows: "The more Facebook friends users have, the more they perform every activity that we explored: friending, liking, private messages, commenting, posting, photo tagging, joining groups and poking." -- Pew Research Center in Washington, D.C.