What is fork?

Any software, cryptocurrencies are software also, need constant updates to repair issues or increase performance. within of cryptocurrency world, those updates are called “forks”. 

Since cryptocurrencies are decentralized networks, all participants within the network – mentioned as nodes – need to follow the same rules so on figure together properly. That set of rules is known as a “protocol”. 

Typical rules during a protocol include the size of a block on a blockchain, the rewards miners receive for mining a replacement block, and much of more.

Types of forks
But both kinds of fork fundamentally change how the protocol of a cryptocurrency works.
Soft Fork is a change during a cryptocurrency protocol that is backward-compatible, meaning that non-updated nodes are still able to process transactions and push new blocks to the blockchain.
Imagine a soft fork which makes a replacement rule lowering block size from 3mb to 2mb. Older nodes will still be able to process transactions and push new blocks that are 2mb or less. But if an older node tries to push a block that’s greater than 2mb to the network, newer nodes will reject the block because it violates the new rules. That encourages older nodes to update to the new protocol since they aren’t as efficient because of the updated ones.
Hard Fork is a change during a cryptocurrency protocol which is incompatible with the previous versions, meaning that nodes that don’t update to the remake won’t be able to process transactions or push new blocks to the blockchain.
They are often used to change or improve an existing protocol, or even to form a replacement, independent protocol and blockchain. Imagine a change during a protocol that increases the block size from 2mb to 4mb. If an updated node tries to push a 3mb block to the blockchain, the older, non-updated nodes won’t see this block as valid, and they’ll reject it.

Planned and Controversial
Depending on things, hard forks can either be planned or controversial.
In a planned fork, participants will voluntarily upgrade their software to follow the new rules, leaving the old version behind. those that don’t update are left mining on the old chain, which only a couple of people are getting to be using. But if the fork is controversial, meaning that there’s a disagreement within the community about the upgrade, the protocol is usually forked into 2 incompatible blockchains — 2 different cryptocurrencies.
Both of the blockchains will have their own community, and thus the developers will progress within the way they believe is that the simplest. Since a fork is based on the primary blockchain, all transactions from the primary blockchain are also copied into the new fork. For example, if you’ve 100 coins of a cryptocurrency called Coin A, and a troublesome fork supported that cryptocurrency creates a replacement cryptocurrency called Coin B, you’ll also get 100 coins of Coin B.
Because of the open-source nature of cryptocurrency and as more individuals and organizations with differing goals enter the crypto space, forks will still be integral to the event of cryptocurrency.