The Reality Check Blockchain is powerful, elegant, and genuinely novel. It’s also slow, expensive, and fragmented. Understanding why takes you from enthusiast to analyst. You’ve now seen what blockchain does and why it’s architecturally remarkable. This final part does something different: it takes a step back and asks why, after more than fifteen years, blockchains

Beyond Currency Recording who paid whom is just the beginning. The moment someone asked ‘what if the ledger could follow instructions?’ — finance changed. Bitcoin’s breakthrough was proving that a shared ledger could record transactions without a trusted middleman. But recording ‘Alice paid Bob’ is a narrow use case. What if the ledger could record

Under the Hood The shared notebook is brilliant — until someone picks up an eraser. Here’s the cryptographic trick that makes the ledger’s history effectively permanent. At the end of Part 1, we had a public ledger shared across thousands of computers. Anyone can read it. That’s the feature. But now a question: if anyone

The Trust Problem How do you send value to a stranger across the world with no middleman — and still be certain nobody cheated? This is the question that invented blockchain. Every time you tap your card at a coffee shop, something remarkable happens in about two seconds. Your bank checks you have the money.