CryptoKitties is one of the world’s first games to be built on blockchain technology—the same breakthrough that makes things like Bitcoin and Ethereum possible. Bitcoin and ether are cryptocurrencies but CryptoKitties are cryptocollectibles. You can buy, sell, or trade your CryptoKitty like it was a traditional collectible, secure in the knowledge that blockchain will track ownership securely.
If you are interested in Blockchain, refer to this Blockchain cat story.