What is Hard Fork?
Hard Fork refers to rule changes(at protocol level) about
- How the Blocks are formed?
- How transactions are created?
Hard Forks are backward-incompatible software updates.
These are generally radical change at protocol level which makes previously valid blocks and transactions invalid, or vice-versa. A hard fork requires all the nodes to upgrade to the latest version of the software. It effectively results in two branches, one that follows the previous protocol and one that follows the new protocol.