$ETH refers to *Ethereum (ETH)*, the second-largest *cryptocurrency* by market capitalization after *Bitcoin (BTC)*. Ethereum is a decentralized platform that enables developers to build and deploy *smart contracts* and *decentralized applications (dApps)*.

Key Features of *Ethereum ($ETH)*:

1. *Smart Contracts*:

- *Ethereum* introduced the concept of *smart contracts*, which are self-executing contracts with the terms directly written into code. These contracts automatically execute actions when certain conditions are met, without the need for intermediaries.

- Smart contracts form the foundation for many *DeFi (Decentralized Finance)* protocols, *NFT (Non-Fungible Token)* platforms, and decentralized applications (dApps) built on the Ethereum blockchain.

2. *Ethereum's Blockchain*:

- Ethereum’s blockchain is an *open-source*, *decentralized* ledger that records all transactions and *smart contract* executions. It allows anyone to create and interact with dApps without needing a centralized authority.

- Ethereum uses *proof-of-work (PoW)* (though it's transitioning to *proof-of-stake (PoS)* with the Ethereum 2.0 upgrade to improve scalability, energy efficiency, and security).