A successful blockchain must be capable of executing upgrades to its protocol in a secure and well ordered fashion. Actuating substantial improvements has proven to be a brutally difficult challenge for many blockchains - in terms of planning, development, implementation, and overall user experience. In the blockchain world, a ‘fork’ can be thought of as a technological split, an update to the code underlying a decentralized ledger resulting in a major modification. Forks have typically fallen into two distinct categories: hardforks and softforks. A hardfork represents an event where the new chain is not meant to be compatible with the old one; a famous example of this is
Bitcoin Cash’s split from Bitcoin. Softforks, on the other hand, encapsulate substantial software changes while retaining reconcilability with the original chain.
Hardforks can occur for many reasons, including innovation, repairing damage from a hack, and failure to reach consensus on a softfork.
Regardless of what necessitates the fork itself, it’s important that the transition from one phase to the next happen securely for everyone involved, from network node operators to everyday users. According to Niahm Ahern and Olga Hyrniuk of Input Output Global, “
Traditionally, when conducting a hardfork, the protocol would stop operating, new rules and changes would be implemented, and the chain would restart.” This method of executing a significant revision to a blockchain with a large user base and a valuable ecosystem in one massive update “
can cause a range of complexities.”
Cardano’s novel approach to implementing protocol improvements is defined by the Hardfork Combinator, which flips the concept of a fork on its head by combining (rather than diverging) the old chain with the new chain. The fact that the combinator can achieve this without sacrificing continuity of user experience or causing network interruption of any kind is a far-reaching accomplishment that sets Cardano apart from its contemporaries.