Read carefully through the fine print of YouTube's terms of service and you might notice that you've affirmed you are old enough to watch it.
"If you are under 13 years of age, then please do not use the service," the terms say. "There are lots of other great web sites for you."
It's a warning that goes unheeded by millions of children around the world who visit YouTube to watch cartoons, nursery rhymes, science experiments or videos of toys being unboxed.
In a formal complaint being filed Monday, child advocates and consumer groups are asking the Federal Trade Commission to investigate and impose potentially billions of dollars of penalties on Google for allegedly violating children's online privacy and allowing ads to target them.
"Google profits handsomely from selling advertising to kid-directed programs that it packages," said Jeff Chester, director of the Center for Digital Democracy, one of the groups that drafted the complaint. "It makes deals with producers and distributors of kids' online programs worldwide. Google has built a global and very lucrative business based on kids' deep connections to YouTube."
YouTube's business model relies on tracking IP addresses, search history, device identifiers, location and other personal data about its users so that it can gauge their interests and tailor advertising to them. But that model isn't supposed to work for American children, who are protected by the Children's Online Privacy Protection Act. That's a 20-year-old law that prohibits internet companies from knowingly collecting personal data from kids under 13 without their parents' consent.
The coalition accuses YouTube of violating COPPA and deliberately profiting off luring children into what Chester calls an "ad-filled digital playground" where commercials for toys, theme parks or sneakers can surface alongside kid-oriented videos.
YouTube said in an emailed statement that it "will read the complaint thoroughly and evaluate if there are things we can do to improve. Because YouTube is not for children, we've invested significantly in the creation of the YouTube Kids app to offer an alternative specifically designed for children."
That toddler-oriented YouTube Kids app, launched in 2015, offers more parental controls but is not widely used — and it uses the same videos and channels that kids can also find on the regular YouTube service.