Ethereum is a decentralized, open-source blockchain featuring smart contract functionality. Ether (ETH) is the native cryptocurrency of the platform. It is the second-largest cryptocurrency by market capitalization, after Bitcoin.[1] Ethereum is the most actively used blockchain.[2][3]

Ethereum was proposed in 2013 by programmer Vitalik Buterin. Development was crowdfunded in 2014, and the network went live on 30 July 2015, with 72 million coins premined.[4][5] The Ethereum Virtual Machine (EVM) can execute Turing-complete scripts and run decentralized applications.[6] Ethereum is used for decentralized finance, and has been utilized for many initial coin offerings.

In 2016, a hacker exploited a flaw in a third-party project called The DAO and stole $50 million of Ether.[7] As a result, the Ethereum community voted to hard fork the blockchain to reverse the theft[8] and Ethereum Classic (ETC) continued as the original chain.[9]

Ethereum has started implementing a series of upgrades called Ethereum 2.0, which includes a transition to proof of stake and an increase in transaction throughput using sharding.