Ethereum (ETH) is the second largest cryptocurrency after Bitcoin, and it is a decentralized platform that supports smart contracts and decentralized applications (dApps). It was launched in 2015 by Vitalik Buterin, and aims to provide an open programming environment for building applications based on blockchain technology. Ethereum relies on a proof-of-stake (PoS) mechanism after the upgrade to "Ethereum 2.0", making it more energy-efficient. ETH is used as a means to pay transaction fees and execute smart contracts. It is also a popular asset in decentralized finance (DeFi) and non-fungible token (NFT) markets. With its continuous development, Ethereum remains a fundamental pillar in the world of cryptocurrencies.