Blockchain Technology

What is Blockchain?

At its core, a Blockchain is simply a digital ledger (a record book) of transactions. However, unlike a traditional bank's ledger which is kept secret and controlled by one central authority, a blockchain is decentralized and distributed across thousands of computers worldwide.

1. How a Blockchain Works

A. The Block

1. Data: Information about the transaction (e.g., Sender, Receiver, Amount).
2. Hash: A unique digital fingerprint for the block. If anyone tries to change the data inside the block, the hash completely changes.
3. Hash of the Previous Block: This is what makes it a 'chain'. Each block points to the hash of the block before it.

B. The Security (Why it's unhackable)

C. Decentralization (Peer-to-Peer Network)

Instead of one central server, every single computer (Node) on the network has a full copy of the blockchain. When a new block is created, it is sent to everyone. If the majority of nodes agree the block is valid (Consensus), it is added to the chain.

2. Key Terminology

• Cryptocurrency: Digital money (like Bitcoin or Ethereum) that uses blockchain technology to secure transactions.
• Smart Contracts: Self-executing contracts where the rules are directly written into lines of code. If conditions are met, the contract executes automatically without a lawyer.
• Mining / Proof of Work: The process where computers solve complex math puzzles to verify transactions and create new blocks. The first to solve it gets a reward.

3. Applications Beyond Bitcoin

• Supply Chain: Tracking a medicine from the factory to the pharmacy. Since blockchain cannot be altered, no one can sell fake medicine along the way.
• Voting Systems: Creating an un-hackable, transparent digital voting system.
• Healthcare: Securely sharing medical records between different hospitals.