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

The native cryptocurrency of the Ethereum network is called Ether (ETH). It serves as both a digital currency and a means of payment for transactions and computational services on the platform. Ether is currently the second-largest cryptocurrency by market capitalization, after Bitcoin.

One of the key innovations introduced by Ethereum is the concept of smart contracts. These are self-executing contracts with the terms of the agreement directly written into code. Smart contracts automatically enforce the rules and conditions defined within them, enabling trustless and transparent interactions between parties.

Ethereum uses a consensus mechanism called Proof-of-Stake (PoS) known as Ethereum 2.0. This upgrade aims to improve scalability, energy efficiency, and security by transitioning from the current Proof-of-Work (PoW) mechanism. Ethereum 2.0 will be implemented in multiple phases, with the first phase, called Phase 0, launched in December 2020.

Ethereum has a vibrant developer community and is widely used for creating decentralized applications, initial coin offerings (ICOs), decentralized finance (DeFi) protocols, non-fungible tokens (NFTs), and more. It has played a significant role in shaping the blockchain and cryptocurrency ecosystem, offering programmable functionality and enabling new possibilities beyond simple digital currencies.

It's important to note that the information provided here is based on the knowledge available up until September 2021, and there may have been further developments and updates to Ethereum since then.