Softfork, Hardfork

Consensus Rule Changes
Blockchain Rule Update Process

Softfork

A softfork is a change to the bitcoin protocol wherein only previously valid blocks/transactions are made invalid. Since old nodes will recognise the new blocks as valid, a softfork is backward-compatible. This kind of fork requires only a majority of the miners upgrading to enforce the new rules.

[wiki]Softfork

관련 BIP

• [BIP16] Pay to Script Hash / Gavin Andresen
• [BIP30] Duplicate transactions / Pieter Wuille
• [BIP34] Block v2, Height in Coinbase / Gavin Andresen
• [BIP65] OP_CHECKLOCKTIMEVERIFY / Peter Todd
• [BIP66] Strict DER signatures / Pieter Wuille

Hardfork

A hardfork is a change to the bitcoin protocol that makes previously invalid blocks/transactions valid, and therefore requires all users to upgrade.

BIP50