A hard fork is a radical upgrade or modification to a blockchain's protocol that introduces changes not compatible with the previous version. This type of fork requires all nodes and users to upgrade to the new protocol version; otherwise, they will be separated from the main network. If there is a split in consensus among the community, the hard fork can result in the creation of two distinct blockchains. Each chain has its own protocol rules and, often, its own cryptocurrency. A notable example of a hard fork is the split of Bitcoin Cash from Bitcoin in 2017, where differing views on how to address scalability issues led to the formation of a new blockchain with larger block sizes. Hard forks are critical in the evolution of blockchain technology, enabling networks to implement substantial updates, address critical issues, or accommodate differing visions within the community.
