What is a fork?
Literally translated, a fork means the fork or branch of the blockchain. By changing the source code a blockchain is changed. If members of the network do not agree with this change, the blockchain is split up and a new branch is created. Then both the old and a new version of the blockchain exist, the latter contains new functions and properties after the fork. The transaction history is the same for both strands until the time of the split. A distinction is made between a Softfork and a Hardfork.
What is the advantage of a fork for the Invenstor?
If a new coin is created in a fork, the owner automatically receives exactly the same amount from the spin-off without having invested new capital again, because both coins had the same blockchain until then.
The prerequisite is that the stock exchange or wallet supports the alternative coin and credits the quantity.
Most famous forks:
The Bitcoin is the Litecoin and the Ethereum is the Ethereum Classic.