After the fork, one chain continues to use the old software while the other chain uses the new software.
This creates two separate cryptocurrencies with their own unique characteristics, such as different transaction validation rules, block sizes, or mining algorithms.
Hard forks can be planned or unplanned, depending on whether the community reaches a consensus on the proposed changes.
A planned hard fork is often done to address issues with the original cryptocurrency or to implement new features.
In contrast, an unplanned hard fork can occur when there is a disagreement among the community about the direction of the cryptocurrency or when a significant bug is discovered in the software.