Hard Fork

A Hard Fork is the permanent separation of a blockchain into two separate networks that do not affect each other. A Hard Fork is performed when there is a significant update to the blockchain code. Some of the projects born from Hard Fork are Ethereum Classic (ETC), Litecoin, and Bitcoin Satoshi Vision (BSV).

Hard Forks can happen for a variety of reasons, including:

1. To fix security issues.
2. The occurrence of irreconcilable disputes within the development community.
3. Restore transactions involved in hacking.
4. Adding new features.
5. Changing the fee structure or rewards for miners.

One of the most recent examples of a hard fork is the Shanghai upgrade, an Ethereum update that enables a withdrawal feature on Ethereum staking (EIP-4895). This system upgrade is a hard fork with EIP-4895 as its main proposal.