Unit 1 · Level 1 · What is a blockchain

Boss: Blockchain foundations

Blocks, consensus, and why any of this works without a boss.

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What you get asked

What breakthrough did Bitcoin's 2008 whitepaper describe?
Published in the middle of the 2008 banking crisis, it solved the double-spend problem with a public ledger instead of a trusted middleman.
Blocks form a chain because each block stores the ___ of the block before it.
Each block carries the fingerprint of its parent. Edit anything in an old block and every fingerprint after it stops matching, so tampering can't hide.
Put the life of a crypto transaction in order:
Sign, verify, package, chain, cement. Each extra block on top makes rewriting your transaction exponentially more expensive.
What do Proof of Work and Proof of Stake BOTH make expensive?
That's the shared genius: attack the network and you torch either your electricity bill (PoW) or your locked stake (PoS). Honesty is simply the cheaper strategy.
Final check: match each term to its meaning
Producers propose, nodes verify, and Ethereum's 2022 Merge proved a live network could swap its entire consensus engine without missing a beat.
A project says it's 'blockchain-powered', but one company runs all the servers and can edit the ledger at will. What is it really?
Boss beaten! The whole point of this unit: no bank, no boss, no quiet edits. When someone CAN quietly edit, it isn't really a blockchain. Ask who holds the pen. 🐜

Blocks, consensus, and why any of this works without a boss.