Hard Fork

A hard fork is a major change in the Blockchain protocol. A hard hork requires all nodes to upgrade to the latest version of the protocol software. Usually, there is a transition period where the miners can show their support of the hard fork. Once a date is set via a specific block number, everybody will need to have updated their software by that time. The ones that fail to upgrade could cause a chain split. The chain with the highest number of nodes or hash rate will be seen as the original c