Ethereum is a decentralized, open-source blockchain platform that enables the development of decentralized applications (DApps) and smart contracts. It was proposed by Vitalik Buterin in late 2013 and launched in 2015.

Unlike Bitcoin, which primarily serves as a digital currency, Ethereum aims to provide a platform for executing programmable contracts and decentralized applications. The native cryptocurrency of the Ethereum platform is called Ether (ETH). Ether is used to pay for transaction fees and computational services on the network.

One of the key features of Ethereum is its ability to support smart contracts. Smart contracts are self-executing contracts with the terms of the agreement directly written into the code. They automatically execute and enforce the agreed-upon rules without the need for intermediaries.

Ethereum introduced the concept of ERC-20 tokens, which are fungible tokens created on the Ethereum blockchain. These tokens have become the foundation for numerous Initial Coin Offerings (ICOs) and tokenized projects, enabling developers to create their own cryptocurrencies and decentralized applications using Ethereum's infrastructure.

In recent years, Ethereum has gained significant attention and popularity, becoming the most actively used blockchain platform for developing decentralized applications and hosting token sales. However, it has faced challenges related to scalability and high transaction fees, which led to the development of Ethereum 2.0.

Ethereum 2.0, also known as Eth2 or Serenity, aims to address these scalability issues by transitioning from a proof-of-work (PoW) consensus algorithm to a proof-of-stake (PoS) mechanism. This upgrade will improve the network's efficiency, security, and sustainability.

Overall, Ethereum has played a crucial role in driving the growth of the decentralized finance (DeFi) ecosystem, enabling projects like decentralized exchanges, lending platforms, and stablecoins. It continues to evolve and innovate, with a vibrant community of developers and users contributing to its development and expansion.