Ethereum is a decentralized platform that runs smart contracts: code that can be used to transfer or exchange money, property, shares, or anything else of value. It is the world’s second largest blockchain after bitcoin. It's designed to be Turing-complete, which means it can do almost any computer program. It uses a cryptocurrency called ether ($ETH) to pay for the gas fees required to perform any on-chain transaction. Imagine it as the world's decentralized super computer and "open state" database.