Consensus rules [Bitcoin]

Consensus rules: the set of rules that a full node enforces to validate a block and its transactions.

Blocks and transactions that don't adhere to the consensus rules will be rejected by full nodes.

As consensuc rules are only concerned with the validity of blocks and transactions, they have nothing to do with the network protocol, even if a change in the network protocol is not backward compatible.

Examples:

• Limited amount of Bitcoins created in a new block
• The 1 MB block size rule

New consensus rules can be added with a soft-fork.

Removing a consensus rule however requires a hard fork.

If there is a disagreement on which concensus rules should be put in place, there will be a fork.

Some suggest to name consensus rules the rules of Bitcoin or hard rules to eliminate confusion about the meaning of »consensus«.