Ethereum is an open-source blockchain platform that allows developers to create and run smart contracts and decentralized applications (dApps) without the need for an intermediary. The digital currency used on the network is known as Ether (ETH), and it is used to pay transaction fees and execute contracts. Ethereum is considered the second largest digital currency after Bitcoin, and it is characterized by its flexibility and support for continuous updates like Ethereum 2.0, which aims to improve transaction speed and reduce energy consumption.