$ETH

Ethereum is a decentralized, open-source blockchain system that enables smart contracts and decentralized applications (dApps) to run on its network. It was proposed in late 2013 by programmer Vitalik Buterin and went live in 2015. Ethereum expands on the concept of blockchain technology, which was first introduced by Bitcoin, but adds the ability to create and execute smart contracts, which are self-executing contracts with the terms of the agreement directly written into code.

Key features of Ethereum include:

1. Smart Contracts: These are self-executing contracts with the agreement terms directly written into code. They run on the Ethereum blockchain and automatically enforce the contract terms without the need for intermediaries.

2. Ether (ETH): Ether is the native cryptocurrency of the Ethereum network. It is used to pay for transaction fees (called "gas") and computational services on the network.

3. Decentralized Applications (dApps): These are applications that run on the Ethereum blockchain, allowing developers to build decentralized systems without relying on a centralized server or authority.

4. Proof of Stake (PoS): Ethereum was initially based on a Proof of Work (PoW) consensus mechanism but transitioned to Proof of Stake (PoS) with the Ethereum 2.0 upgrade, aimed at making the network more energy-efficient and scalable.

5. ERC-20 and ERC-721 Tokens: Ethereum enables the creation of various token standards like ERC-20 for fungible tokens (such as stablecoins or utility tokens) and ERC-721 for non-fungible tokens (NFTs), which represent unique assets.

6. Decentralized Finance (DeFi): Ethereum has become the foundation for DeFi projects, which aim to recreate traditional financial systems (like lending, borrowing, and trading) in a decentralized manner using smart contracts.

Ethereum is widely regarded as the second most significant cryptocurrency platform, after Bitcoin, in terms of adoption and development.