Nakamoto Consensus

Nakamoto consensus is the rule set introduced with Bitcoin that lets an open network agree on a single transaction history without any central coordinator. It combines three pieces: proof of work, which makes producing a block costly; a block reward that pays whoever does that work; and the longest-chain rule, which tells every node to follow the branch with the most accumulated work. Agreement is probabilistic rather than final — a block becomes harder to undo as more blocks pile on top, which is why exchanges wait for several confirmations. The design assumes most hashing power behaves honestly, because rewriting recent history means redoing the work behind it. Later chains swapped proof of work for proof of stake but kept the same core idea: make rewriting history expensive.