Ethereum
Ethereum is a programmable blockchain platform that runs smart contracts and decentralized applications, with its own cryptocurrency, ether (ETH).
Proposed by Vitalik Buterin and launched in 2015, Ethereum extended the blockchain idea beyond payments. Developers can write smart contracts, programs that run automatically on the network when conditions are met. These power decentralized finance (DeFi), stablecoins, NFTs and many other tokens.
Ether is used to pay transaction fees, called gas, and as collateral in many applications. Unlike bitcoin, ether has no fixed maximum supply; issuance and fee burning together determine whether total supply grows or shrinks over time.
In September 2022, an upgrade known as the Merge switched Ethereum from proof of work to proof of stake, reducing its energy use by more than 99% according to the Ethereum Foundation. Validators now lock up ether, a process called staking, to secure the network and earn rewards.
Ether is the second-largest cryptocurrency by market capitalization and, like bitcoin, can be highly volatile. US investors can buy it on crypto exchanges or through spot ether ETFs, which began trading in 2024.