3. What is Blockchain?
Blockchain is the technology behind cryptocurrencies like Bitcoin and Ethereum. Think of it as a digital ledger or record book that keeps track of all transactions — but instead of being stored in one place (like a bank), it's stored across thousands of computers around the world.
The word “blockchain” comes from how the data is stored:
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"Block" = a group of transaction records
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"Chain" = all blocks linked together in time order
Once a block is full of transaction data, it is linked to the previous block, forming a chain — hence, the name blockchain.
✅ Key Features of Blockchain:
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Decentralized: No single person, company, or government controls it
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Transparent: Everyone can see the transactions
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Immutable: Once data is recorded, it cannot be changed or deleted
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Secure: Uses advanced cryptography to protect data
💡 Real-Life Uses of Blockchain:
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Cryptocurrencies like Bitcoin and Ethereum
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Smart Contracts (auto-executing digital contracts)
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Supply Chain Tracking
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Voting Systems
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Digital Identity Verification
📌 Example:
When you send Bitcoin to someone, that transaction is stored on a block. Once verified by the network, the block becomes part of the chain — permanently and publicly.
