Twelve-year-olds are not welcome on Facebook. The social network could allow children if it wanted, but federal law requires commercial websites to "obtain verifiable parental consent for the collection, use, or disclosure of personal information from children."
Rather than deal with the hassle and expense of collecting permission slips from millions of parents, Facebook decided to simply ban anyone under the age of 13.
But a lot of websites have chosen a different path. Amazon, Netflix, and Apple's iTunes – three services ostensibly designed for adults and their credit cards – have created separate online playgrounds for kids. Here's a quick guide to how they work.
Kindle FreeTime Unlimited: Amazon set up special junior accounts for Kindle Fire owners. The service unlocks a trove of books, movies, TV shows, and applications that are appropriate for children ages 3 to 8.
Amazon designed the plan to give children a sense of independence. Each child may set up a personalized account with unlimited access to the Kindle FreeTime library. Parents pay a monthly fee of $5 per child or $10 for the whole family. (Amazon Prime subscribers pay a few dollars less.)
While kids can read and watch whatever they want, parents may limit the amount of screen time. For example, you could restrict your son to only one hour of video-watching a day but let him read for as long as he wants.
Each second-generation Kindle Fire and Kindle Fire HD comes with the FreeTime app installed. The app is not available on first-generation Kindle Fire tablets.
Netflix Just for Kids: When Netflix started building its Web video empire, the company cut deals with movie studios and TV networks to stream just about everything it could get its hands on. Last year, the strategy changed. Netflix spent 2013 refining its catalog. That means letting some contracts lapse, but still loading up on quality dramas and children's shows.
Netflix subscribers watched more than 2 billion hours of children's programming in 2012, much of it using the Just for Kids tab.
This feature is less structured than Amazon's. Just for Kids is more of a category than a separate service. There are no unique profiles or individualized recommendations. But it also means that there's no extra monthly fee.
Just for Kids sorts TV shows and movies into kid-friendly categories (girl power, talking animals, superheroes) or by favorite characters (Dora, Tinker Bell, Batman). Netflix has curated all of this programming for children 12 and under.
And just as Netflix has original series such as "House of Cards" for adults, it has teamed up with Dreamworks to create "Turbo F.A.S.T." for kids. The animated show is based on the upcoming Dreamworks movie "Turbo," about a superspeedy snail that competes in the Indianapolis 500.
iTunes Allowance: Rather than expect parents to hand over their credit card every time a child wants to download a new song, Apple has set up iTunes Allowance. The program automatically bills parents each month for a set amount and moves that money over to the child's account.
Parents can turn on this feature in iTunes 11 by opening up the iTunes Store and selecting "Send iTunes Gifts" from the Quick Links section. From there, click on "Learn More About Gifting" and finally "Set Up an Allowance." As with Facebook, Allowance only works with children 13 and older.
While younger kids may not have their own accounts, Apple offers parental controls so children and parents can share a single library. The iTunes Preferences panel lets parents restrict access to mature movies, TV shows, and apps. Parents can also flat-out disable Internet radio stations, podcasts, music with explicit language, or access to the iTunes Store.
In iTunes 11, the Preferences panel is located under the Edit menu on PCs or under the iTunes menu on Macs.
For more on how technology intersects daily life, follow Chris on Twitter @venturenaut.