A fork in a blockchain network happens when any changes to the underlying protocol take place or fundamental aspects pertaining to cryptocurrency need to change. There are two kinds of forks – Soft fork and Hard fork. Soft fork occurs when the change is backward compatible, and users only need to upgrade their software.

Hard fork takes place when the change is not backward compatible, and the users have to move to the new chain or else take the risk of not being able to mine any blocks further. Hard forks usually arise on account of disagreements in the community with respect to proposed changes and their implementation.

Bitcoin Cash, Bitcoin Gold and Ethereum Classic are examples of cryptocurrencies that have appeared owing to Hard Forks.