🧱 What is Blockchain?
🧱 What is Blockchain?
Blockchain is the technology behind cryptocurrencies — like the engine inside a car. You don’t always see it, but it’s doing all the hard work.
🔍 Simple Definition
A blockchain is a digital ledger — like an online notebook — that records every transaction made with a cryptocurrency.
Once something is written in it, it can't be changed. That makes it super trustworthy.
📦 How It Works (In Simple Terms)
A new transaction happens (like Alice sends BTC to Bob).
That transaction is grouped into a "block" with others.
The block is verified by computers on the network (called nodes).
Once verified, it's added to the "chain" — the blockchain.
Everyone can see it, but no one can change it.
✅ It’s like writing on a whiteboard with a permanent marker.
🔐 Why Is Blockchain Secure?
Decentralized: No single person or server controls it.
Transparent: Anyone can view the data.
Immutable: Once added, data can’t be altered.
Cryptography: Every block is secured with complex math.
🧠 Real-Life Examples
Bitcoin Blockchain: Just tracks BTC transactions.
Ethereum Blockchain: Also runs apps and smart contracts.
Solana Blockchain: Fast transactions + low fees.
🧠 Each blockchain is like a different internet for money and data.
💡 Use Cases Beyond Crypto
Supply chain tracking (like tracing food origin)
Voting systems
Medical record storage
NFTs and gaming
🧪 In Summary
Blockchain is the foundation of Web3 and cryptocurrencies. It’s a powerful, secure, and transparent way to record data — and it’s only getting started.
🧭 Next Lesson: What is a Token?
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