I just signed up to this website and noticed no one answered your question. CryptoKitties is a great way to explain how "things" are becoming digital. Think of CryptoKitties like your digital baseball card...expect it's a cat card. These cards are digital tokens called an NFT (non-fungible token). All tokens can have different behaviors and attributes. For more information on tokens you can visit the Enterprise Ethereum Alliances Token Toxonomy Initiaive where they define these tokens. Would love to chat more if you have questions.