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 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 on 30 July 2015. The platform allows developers to deploy permanent and immutable decentralized applications onto it, with which users can interact. Decentralized finance (DeFi) applications provide a broad array of financial services without the need for typical financial intermediaries like brokerages, exchanges, or banks, such as 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 (ICOs)... Buterin argued that Bitcoin and blockchain technology could benefit from other applications besides money and needed a scripting language for application development that could lead to attaching real-world assets, such as stocks and property, to the blockchain... Ethereum was announced at the North American Bitcoin Conference in Miami, in January 2014. During the conference, Gavin Wood, Charles Hoskinson, and Anthony Di Iorio (who financed the project) rented a house in Miami with Buterin to develop a fuller sense of what Ethereum might become. Di Iorio invited friend Joseph Lubin, who invited reporter Morgen Peck, to bear witness. Peck subsequently wrote about the experience in Wired. Six months later the founders met again in a house in Zug, Switzerland, where Buterin told the founders that the project would proceed as a non-profit. Hoskinson left the project at that time. https://en.wikipedia.org/wiki/Ethereum
Open-source development is currently underway for a major upgrade to Ethereum known as Ethereum 2.0 or Eth2. The main purpose of the upgrade is to increase transaction throughput for the network from the current of about 15 transactions per second to up to tens of thousands of transactions per second. The stated goal is to increase throughput by splitting up the workload into many blockchains running in parallel (referred to as sharding) and then having them all share a common consensus proof-of-stake blockchain, so that to maliciously tamper with any singular chain would require one to tamper with the common consensus, which would cost the attacker far more than they could ever gain from an attack.
Bitcoin's primary use case is that it is a store of value and a digital currency. Ether can also be used as a digital currency and store of value, but the Ethereum network makes it also possible to create and run decentralized applications and smart contracts. Ethereum blocks are validated approximately every 12 seconds on Ethereum as opposed to approximately every 10 minutes on Bitcoin. Additionally, Bitcoin has a fixed supply of 21,000,000 coins, whereas Ethereum has no supply cap... The EVM's instruction set is Turing-complete. Popular uses of Ethereum have included the creation of fungible (ERC20) and non-fungible (ERC721) tokens (NFT) with a variety of properties, crowdfunding (e.g. initial coin offerings - ICO), decentralized finance (DeFi), decentralized exchanges, decentralized autonomous organizations (DAOs), games, prediction markets, and gambling.