What is Blockchain?

Imagine an accounting ledger duplicated simultaneously on thousands of machines, where pages can only be added — never erased or rewritten — and every new page is validated by the whole network. That is blockchain, and its genuinely novel property is trust between parties who do not know each other, achieved without a central authority; it is why cryptocurrencies function with no bank in the middle. Beyond crypto, the serious applications are niche: traceability across multi-company supply chains, notarial proof that a document existed at a date, contracts that execute themselves. The uncomfortable truth for an ordinary business is that in nearly every routine scenario, a conventional database is faster, cheaper and simpler to run; the distributed ledger earns its cost only when several organisations that cannot extend each other trust must share one record of truth. So when a proposal arrives wearing the word, the first sober question is: what does this solve here that a plain database would not solve for a tenth of the money? Knowing that answer pattern protects budgets better than any whitepaper.