🔗 Blockchain

What Is a Blockchain?

A blockchain is a special kind of database shared by many computers. It stores information in ordered blocks, linked like a chain. Once data is recorded, it is very hard to change.

Key ideas:

• Shared record
• Hard to edit the past
• Everyone can check the same history

Why Blockchains Matter

Blockchains try to solve a big problem: trust.

Instead of trusting one company to keep honest records, many computers keep copies and check each other.

Benefits:

• Less single point of failure
• Harder to secretly change data
• Easier to verify history, like money transfers

They are often used for cryptocurrencies, but also for tracking goods or documents.

Centralized vs Decentralized

Centralized system:

• One main server or company
• If it fails or cheats, everyone suffers

Decentralized system:

• Many nodes (computers) share control
• No single boss of the data

Blockchain is usually decentralized, so power and responsibility are spread out.

Public and Private Blockchains

Not all blockchains are open to everyone.

• Public: anyone can join, view data, and help secure it (example: Bitcoin)
• Private: only invited members can use it (example: within a company group)

Both use similar tech, but the rules, access, and trust model are different.