Hard fork
This is Head Wang Blockchain Academy, grow up with the best blockchain people! Today I will talk about hard forks.
There are many nodes on the blockchain. When a new version of the software appears, not all nodes are willing to upgrade, and not all nodes can react immediately. Nodes react differently to the new version of the software, resulting in different fork results.
According to whether the upgraded blockchain can be compatible with the old blockchain, the forks are divided into "hard forks" and "soft forks", and the incompatible ones are hard forks.
A hard fork means that when the Bitcoin block format or transaction format (consensus mechanism) changes, the unupgraded node refuses to verify the block generated by the upgraded node, and then everyone continues the chain that they think is correct, so it is divided into two chain.
Take Bitcoin as an example. In July 2017, in order to solve the congestion problem of the Bitcoin blockchain, some Bitcoin enthusiasts proposed a Bitcoin Cash (BCH) fork plan, but some miners in the community did not support it. The dominant Bitcoin hard fork was formed. The Bitcoin blockchain became the Bitcoin (BTC) network and the Bitcoin Cash (BCH) network, and Bitcoin Cash (BCH) has become the most successful hard fork so far. Bifurcation.
In the Bitcoin (BTC) network, some nodes are upgraded and run the new client Bitcoin Cash (BCH). Although the upgraded node still receives the transactions and blocks generated by the old node, in turn, the unupgraded nodes will reject the transactions and blocks generated by the upgraded node, and at the same time, they will send temporary prohibition and disconnection to those judged by them. Nodes for invalid transactions and blocks.
Therefore, the network is divided into two parts: the Bitcoin (BTC) network and the Bitcoin Cash (BCH) network. Unupgraded nodes are only allowed to connect to unupgraded nodes, and upgraded nodes can only be connected to upgraded nodes. Due to the connection to two separate networks, the partition of the network prevents miners who mine according to their own rules from receiving each other's blocks.
The nodes that use the new client of Bitcoin Cash (BCH) mine based on the new rules, and the nodes that have not been upgraded continue to mine based on the old rules. This also causes the two chains of the fork to have different computing power. This is also the Bitcoin (BTC) network. The reason is different from Bitcoin Cash (BCH) network computing power.