Ethereum (English: Ethereum) is an open source public blockchain platform with smart contract function. A decentralized virtual machine (called Ethereum virtual machine) is provided through its dedicated cryptocurrency, ether (also known as "Ether") to process point-to-point contracts. From 2013 to 2014, the concept of Ethereum was first proposed by the programmer vitalikbutellin inspired by bitcoin to the effect that "the next generation cryptocurrency and decentralized application platform" began to develop through ICO crowdfunding in 2014. As of june2018, Ethereum is the cryptocurrency with the second highest market value. Ethereum is also known as the "second generation blockchain platform", second only to bitcoin. Compared with most other cryptocurrencies or blockchain technologies, Ethereum features the following: smart contract: a program stored on the blockchain is run by each node, and the person who needs to run the program pays a service fee to the miners or stakeholders of the node. Tokens: smart contracts can create tokens for distributed applications. The tokenization of distributed applications aligns the interests of users, investors, and managers. Tokens can also be used for the first token issue. Uncle block: a shorter blockchain that is not timely incorporated into the parent chain due to its slow speed, so as to increase the transaction volume. The related techniques of directed acyclic graph are used. Proof of stake: it is more efficient than workload proof, which can save a lot of computer resources wasted in mining, and avoid network centralization caused by special application of integrated circuits. Plasma (under test): a smaller branch blockchain is used to calculate, and only the final result is written into the main chain, which can increase the workload per unit time. (not yet implemented) state channels: a lightning network with the principle similar to bitcoin, which can improve transaction speed, reduce the burden of blockchain and im