The subscription brings children characters like Elmo, Dora, Thomas & Friends, Cinderella, Buzz Lightyear, Lightning McQueen and Curious George. With individual profiles, everything in the child's library is their own. In other words, children do not have to share a home screen with siblings or parents. And that means no losing their place in a movie or TV show when someone else picks up the Kindle Fire.

"As a parent, it's hard to predict what my daughter is going to enjoy, or which movie she's going to watch 50 times in a row -- so I buy a range of content and hope for the best -- but I get it wrong frequently," said Peter Larsen, vice president of Amazon Kindle. "FreeTime Unlimited gives kids the freedom to explore age-appropriate content on their own and pick for themselves what they want to watch, play or read next."

Under the Hood

Here's how it works: When a parent signs up for FreeTime Unlimited, thousands of content titles automatically appear. Those titles are sorted by their children's age and gender, alongside the titles parents have already approved from their own collection of content. The pre-screening makes it possible to allow children to pick the content they want to view without help from mom and dad.

FreeTime Unlimited also offers many of the most popular children's games, with all in-app ads and in-app purchasing removed. Games include Disney's bestselling Where's My Water? and Where's My Perry?

FreeTime Unlimited includes movies from Barney, Thomas & Friends, Bob the Builder, Fireman Sam and Angelina Ballerina, as well as TV shows like Sesame Street, SpongeBob SquarePants, Dora the Explorer and Blue's Clues.

Amazon's Vending Machine

Avi Greengart, principal analyst at Current Analysis, told us Amazon understands that consumers who own a Kindle usually also own one or two other computing devices.

"Keep in mind that the Kindle is basically a vending machine, so they are selling you the ability to buy their content. If they can sell you the ability to buy commercial video content, that's even better," Greengart said.

"Children's books and children's videos, those are really sticky. For many adults, it's a rental model, where really you don't necessarily want to own it. But with kids, you generally do want to own it because the child wants to watch it 4 billion times."

Of course, Amazon is not the only mobile -device maker to segregate content. Barnes & Noble has user accounts and Microsoft Windows Phone has Kid's Corner, which allows parents to set up a sandbox so children can use it without accessing e-mail and social media accounts.

"Amazon would like to sell you more content and more types of content," Greengart said. "They understand that the Kindle is not really designed to necessarily replace your computer but to supplement it, and anything they can do to broaden the reach into your household will increase the sales of the product."

Recommended Reading: The History of Wireless: How Creative Minds Produced Technology for the Masses Synopsis: The History of Wireless reads like a novel. It chronicles the discoveries and inventions that led to today's mass market. Available for the Kindle and in paperback.

Gift Suggestion: Give your favorite children the gift of an amazing adventure in reading. Check out one of the hottest new series of the year: The Mason Dexter Adventure Series chronicles the adventures of Mason Dexter, a resourceful middle-school boy who builds amazing tech gadgets and saves America from impending doom. The Mason Dexter Adventure Series is available now on Amazon.com. Perfect to read on the iPad, Kindle, Android eBook readers, or any computer with Amazon's free Kindle app.

Melanie: