The majority of cryptos have been created as a result of a fork. The number of forks is increasing day by day, but it's important to know the differences between a fork and a hard fork. Let's use an example to explain.
Litecoin - was originally a fork of Bitcoin. Its foundations are built on the source code of BTC, but its blockchain was started from block 0.
Bitcoin Cash - is a hard fork of Bitcoin. Similarly to the fork - the foundations are built using the source code of Bitcoin, yet the blockchain was started from block 478559. As a result of that, the network was effectively split into 2 and 2 independent from each other blockchains were created. Because the split happened at the exact block - both networks have the same transaction history before block 478559 and this in effect allows all Bitcoin (BTC) holders to get the same amount of Bitcoin Cash (BCH) in the 1:1 ratio.
Nowadays, no one uses forks because hard forks allow for a quicker way to get people onboard with the project and get an acceptable coin price. Saying that that difference between forks and hard forks is fading away. More often than not, cryptos like Bitcoin Cash, Bitcoin Gold and Litecoin Cash are called forks.