A fork is a change in the rules of a network; there are two types of forks: soft and hard. A hardfork leads to the creation of a new cryptocurrency.
A fork is a change in the rules of the network by which a block in a blockchain is recognised as genuine, a kind of unbundling, hence the name – from the English fork. There are two types of forks: soft and hard.
Soft – is a mild form of unbundling, where nodes from an older version can communicate with nodes from a newer version. A softfork does not result in a new currency.
Hard – serious innovations that split the chain into two nodes unable to interact with each other. This is how Bitcoin Cash, Bitcoin Gold, Ethereum Classic appeared, for example.