Ethereum is a decentralized, open-source blockchain with smart contract functionality. Ether (ETH or Ξ) is the native cryptocurrency of the platform. After Bitcoin, it is the second-largest cryptocurrency by market capitalization. Ethereum is the most actively used blockchain.Ethereum was proposed in 2013 by programmer Vitalik Buterin. In 2014, development was crowdfunded, and the network went live with an initial supply of 72 million coins on 30 July 2015. The platform allows developers to build and operate decentralized applications that users can interact with. Decentralized finance (DeFi) applications provide a broad array of financial services without the need for typical financial intermediaries, such as brokerages, exchanges, or banks, allowing cryptocurrency users to borrow against their holdings or lend them out for interest. Ethereum also allows for the creation and exchange of NFTs, which are non-interchangeable tokens connected to digital works of art or other real-world items and sold as unique digital property. Additionally, many other cryptocurrencies operate as ERC-20 tokens on top of the Ethereum blockchain and have utilized the platform for initial coin offerings.
In 2016, a hacker exploited a flaw in a third-party project called The DAO and stole $50 million of Ether. As a result, the Ethereum community voted to hard fork the blockchain to reverse the theft and Ethereum Classic (ETC) continued as the original chain.Ethereum has started implementing a series of upgrades called Ethereum 2.0, which includes a transition to proof of stake and aims to increase transaction throughput using sharding.