Ethereum is a decentralized open-source blockchain system that has its own cryptocurrency, Ether (ETH), and is currently the second-largest cryptocurrency by market capitalization, following Bitcoin.
The most important feature of Ether is its use for executing Ethereum smart contracts. Ethereum is a blockchain technology with smart contract functionality, supporting many derivative applications. Currently, many smart contract applications are built on Ethereum.
Thanks to Ethereum's underlying application framework, various applications can be developed on it, such as Initial Coin Offerings (ICO) for fundraising, wallets, derivative contracts, decentralized finance (DeFi), protocol contracts, lending, games, and NFT issuance, among others.
Reference: CoinMarketCap