What is Fork

Forks are essentially split in the blockchain network. A Fork occurs when changes, whether intentional or accidental, take place in the original rules of the blockchain network.

Accidental forks 

Accidental forks occur when different miners discover, for instance, two new blocks on a network at nearly the same time. Then the network will be temporarily divided into two different chains. Miners will thusly be split onto these two chains until new blocks are added to one of these chains thereby creating a longer chain. The longer chain will eventually be kept and the other will be abandoned.

What is mining? Why do miners engage in mining? Please refer to the content: What is mining?

Intentional forks

Intentional forks refer to the case where the rules of a blockchain are modified on purpose. Older nodes, for some reason, may not choose to upgrade to the newest version. The original blockchain will diverge into two chains depending on whether the nodes on each chain choose to or not to upgrade. An intentional fork can be further categorized into Soft Fork and Hard Fork.

• A Soft Fork is generally known as a backward-compatible update, where the older nodes will recognize new blocks as valid. It implements the new rules while it does NOT require all nodes to upgrade.
• A Hard Fork, by contrast, DOES require ALL nodes to upgrade to the latest version which is not backward-compatible with older nodes, and an entirely new blockchain will thusly be created. A typical example is the hard fork of Bitcoin in 2017 into $BTC and $BCH and it aimed to solve the scalability problem of the original Bitcoin. Another is how Ethereum hard-forked into $ETH and $ETC in an attempt to recover lost funds from the DAO Attack in 2016.

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