🚀 Objective:

• Understand blockchain technology deeply, with Ethereum as a case study.
• Learn how Ethereum works under the hood — not just at the surface.
• Set up MetaMask for wallet interaction, Sepolia Testnet for deploying contracts, and explore Etherscan to view live transactions.
• Become proficient in using blockchain exploration tools for security and development.

🧠 What is Blockchain?

A blockchain is a distributed, decentralized ledger used to store data in a secure and immutable way. Here’s a breakdown of the essential components of blockchain:

🔑 Key Characteristics of Blockchain:

1. Decentralized:
   • There’s no single point of control (no central authority). Every node (computer) in the network has access to the same data and participates in consensus.
2. Immutable:
   • Once data is recorded on the blockchain, it cannot be altered. This is achieved by cryptographic hashing and a consensus mechanism.
3. Transparency:
   • All transactions are visible to anyone. This ensures accountability and prevents fraudulent behavior.
4. Consensus Mechanism:
   • Blockchain uses a protocol that enables distributed nodes to agree on the state of the blockchain. Common consensus methods are:
     • Proof of Work (PoW): Used in Bitcoin and Ethereum (prior to 2022). Miners solve cryptographic puzzles to validate transactions.
     • Proof of Stake (PoS): Ethereum has moved to PoS. Validators stake their ETH to validate transactions and add blocks to the chain.

🧠 How Does Blockchain Work?

• Blocks contain data (transactions).
• Each block is linked to the previous one using a hash. This forms a continuous chain — hence the name blockchain.
• Transactions are validated by nodes through the consensus mechanism.
• Cryptographic hashing ensures that once a block is added, it’s secure and immutable.

📘 Ethereum Blockchain Overview