Ethereum (ETH) is a decentralized, open-source blockchain platform that was launched in 2015. It was created by Vitalik Buterin and a group of developers, with the aim of creating a platform that could enable the development of decentralized applications (DApps) and smart contracts.

ETH is the native cryptocurrency of the Ethereum network and is used to facilitate transactions on the platform, as well as to pay fees for using the network's resources. It is currently one of the largest cryptocurrencies by market capitalization, and is widely traded on many cryptocurrency exchanges.

One of the key features of Ethereum is its ability to enable the creation of decentralized applications (DApps) and smart contracts. DApps are essentially applications that run on the Ethereum blockchain, and are designed to be more secure, transparent, and resistant to censorship than traditional centralized applications. Smart contracts, on the other hand, are self-executing contracts that automatically enforce the rules and obligations of the contract when certain conditions are met.

Overall, Ethereum has become a major player in the cryptocurrency space, and its technology has inspired the development of many other blockchain platforms and decentralized applications.