#Ethereum
**Ethereum: The Decentralized World Computer**
### **1. Introduction to Ethereum**
Ethereum, launched in 2015 by Vitalik Buterin and a team of developers, is a decentralized, open-source blockchain platform designed to go beyond Bitcoin’s peer-to-peer cash system. It introduced **smart contracts**—self-executing code that automates agreements—and became the foundation for decentralized applications (dApps), decentralized finance (DeFi), and non-fungible tokens (NFTs).
---
### **2. Key Features**
- **Smart Contracts**: Code that runs on the blockchain without intermediaries (e.g., automating loans or insurance payouts).
- **Ethereum Virtual Machine (EVM)**: A global, decentralized computer that executes smart contracts.
- **Decentralized Applications (dApps)**: Apps built on Ethereum, such as Uniswap (DeFi) and OpenSea (NFT marketplace).
---
### **3. Ethereum 2.0 and The Merge**
In September 2022, Ethereum completed **The Merge**, transitioning from energy-intensive Proof of Work (PoW) to Proof of Stake (PoS). Benefits include:
- **~99.95% reduced energy consumption**.
- **Staking**: Users lock ETH to secure the network and earn rewards (over 26 million ETH staked as of 2023).
- **Scalability Roadmap**: Future upgrades like sharding aim to increase transaction throughput.
---
### **4. Token Standards**
- **ERC-20**: The standard for fungible tokens (e.g., stablecoins like DAI).
- **ERC-721**: For non-fungible tokens (NFTs), enabling digital art and collectibles.
- **ERC-1155**: Hybrid tokens for gaming/metaverse assets.
---
### **5. Use Cases**
- **DeFi**: Lending (Aave), decentralized exchanges (Uniswap), and yield farming.
- **NFTs**: Digital ownership for art, music, and virtual real estate.
- **DAOs**: Decentralized organizations governed by token holders (e.g., MakerDAO).
---
### **6. Scalability Solutions**
Ethereum’s high gas fees and congestion led to **Layer 2 solutions**:
- **Rollups** (Optimism, Arbitrum): Bundle transactions off-chain.
- **Sidechains** (Polygon):
