What does consensus mean in Bitcoin?
Correct answer
Answer D: Shared rules lead to the same valid transaction history.
Quick explanation
Nodes with compatible rules can recognize the same valid transaction history. This shared recognition under a set of rules is part of Bitcoin's consensus.
Detailed explanation
In Bitcoin, consensus means that participants applying compatible consensus rules arrive at the same view of which transactions and blocks are valid. Full nodes independently verify the data they receive. If they apply compatible rules and receive the same valid chain, they can reach the same result without asking a central authority.
This is not a one-node-one-vote election. Miners propose blocks, and proof of work helps order valid chain candidates. A block that violates a full node's rules will still be rejected by that node even if substantial computing power was used to produce it.
Rule changes also require coordination: users, developers, businesses, exchanges, wallet providers and miners decide which software they actually run. If incompatible rules remain in use, the network can split. Bitcoin consensus therefore combines technical validation with voluntary social and economic coordination.
Key takeaway
Bitcoin's rules work because participants check them themselves and voluntarily use compatible rules together.
Common misconception
Consensus rules are determined neither by a vote based on node count nor solely by miners or developers. Every validating node enforces the rules it runs.
Sources used
Bitcoin Developer Guide - Block Chain
This source is mainly intended for developers. The relevant information may therefore be harder to find.
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