Facebook has an ugly little secret, a number disclosed nowhere in its voluminous filings to become a public company and now only vaguely addressed by corporate officials.
An estimated 5.6 million Facebook clients -- about 3.5 percent of its U.S. users -- are children who the company says are banned from the site.
Facebook declines to acknowledge that many of its efforts to block children are not working.
Yet, Facebook has made some progress in identifying preteens and excluding them from the site. A June Consumer Reports study showed that Facebook eliminates as many as 800,000 users under age 13 in a year through its tiered screening process, which the company declines to describe. The study still estimates 5.6 million children are on Facebook, a figure that experts say includes many who create accounts with help from their parents.
Children who aren't savvy enough to game Facebook's system often get parental help, according to a 2011 study headed by Danah Boyd, a senior researcher at Microsoft Research. She found that 55 percent of parents of 12-year-olds said that their child was on Facebook and that 76 percent of those had helped the child gain access.
The Consumer Reports data comes from a January 2012 survey of 2,002 adults with home Internet. Participants were chosen by TNS, a research firm. The margin of error is plus or minus 2 percentage points.
A Reuters test of Facebook's signup process shows that a child could bypass the site's screening features with relative ease. The site effectively blocked a fictitious sign-up from an underage prospective user. But after an hour's wait, the site accepted a sign-up using the same name, email, password and birthday but citing a different birth year.
Facebook declined to discuss the data or describe its efforts to ban children. Spokesman Frederic Wolens said in an email that Facebook is "committed to improving protections for all young people online".