A blockchain fork refers to a split in a blockchain's network, creating several updated versions of a blockchain.

As blockchains are open-source, users can propose modifications and improvements. If the miners of the network cannot reach a unanimous decision on a proposition, the blockchain will split into several networks. At this point, miners can choose which network they want to continue using.

There are two kinds of blockchain forks:

• hard forks refer to permanent drastic changes in the network requiring miners to update their software, Bitcoin Cash is a hard fork of Bitcoin for example;
• soft forks refer to changes that can be reversed on the blockchain. For a soft fork to be effective, the majority of miners need to upgrade their system.