Bitcoin fork means the blockchain of bitcoin is forked.

It’s well known that bitcoin blockchain is chained data structure under POW consensus mechanism. All the participants follow the same rules thus to synchronously download and upload all the information.

With the growth of bitcoin community, some of the participants develop different opinions towards the consensus mechanism. Some of them want to modify the rules of bitcoin blockchain thus different technology solution is developed.

 

Bitcoin fork includes hard fork and soft fork.

 

Hard fork

Bitcoin hard fork means both the two different chains are able to verify the completed transactions before the forked chain is produced. From the fork block height, these two chains become two independent bitcoin blockchain whose transactions can’t be verified by the other. The new forked chain follows its own rules to fulfil the process of verifying transactions.

Some successful hard fork are Bitcoin Core, Bitcoin Cash, Super Bitcoin and many more.

If the hard fork is succeeded, there will be a new chain produced, but it needs massive calculating power to support hard fork otherwise the hard fork will be failed. Even the hard fork is succeeded, if there is no enough calculating power to maintain, the new chain will be disappeared also.

 

Soft fork

Bitcoin soft fork means when a new chain is forked according to new rules, all the transaction information (before soft fork happens or after) can be verified on both these two chains. Technology used to maintain the new chain is extremely complicated which requires it to compatible with multiple technical standards. Because of the difficulty and complexity, soft fork could be possibly abandoned.

    Segwit is an example of bitcoin soft fork.