Ethereum is an open-source, decentralized blockchain platform that enables the creation and execution of smart contracts. It was proposed by Vitalik Buterin in late 2013 and launched in 2015.

Unlike Bitcoin, which primarily focuses on digital currency, Ethereum serves as a platform for building decentralized applications (DApps). It has its native cryptocurrency called Ether (ETH), which is used for transacting and incentivizing participants on the Ethereum network.

Ethereum enables developers to create and deploy smart contracts, which are self-executing agreements or protocols with the terms of the agreement directly written into code. Smart contracts automatically perform actions once specific conditions are met, removing the need for intermediaries.

It introduced the concept of ERC-20 tokens, which are widely used for Initial Coin Offerings (ICOs) and the creation of various tokens on the Ethereum blockchain. Additionally, Ethereum has introduced various improvements over time, including a transition from a Proof-of-Work (PoW) consensus mechanism to Proof-of-Stake (PoS) through its Ethereum 2.0 upgrade.

The Ethereum network allows developers to build decentralized applications for various use cases, such as decentralized finance (DeFi), non-fungible tokens (NFTs), gaming platforms, decentralized exchanges, and more. Its flexibility and programmability have made it a popular choice for blockchain-based development.

Ethereum's vision is to create a globally accessible, censorship-resistant, and decentralized platform that empowers developers to build innovative applications through the use of smart contracts and blockchain technology.