CoinucationFork
A fork is a change to a blockchain's rules or a split in its history, which can produce either an upgrade or two separate chains.
A fork happens when a blockchain's software or its chain of blocks diverges. In software terms, a fork is a change to the protocol rules. In chain terms, a fork is a point where two valid blocks are built on the same parent, creating two competing histories. Brief forks of the second kind happen naturally and resolve when one branch gets longer.
Soft forks tighten the rules so that old nodes still accept new blocks. Bitcoin's SegWit upgrade in 2017 and Taproot in 2021 were soft forks. Hard forks change the rules in a way that old nodes reject, so everyone must upgrade or the network splits. Ethereum's upgrades are generally hard forks that the whole community coordinates to adopt.
The word fork is also used when developers copy an open-source project's code to start a new one. Litecoin began as a fork of Bitcoin's code in 2011, and SushiSwap was a fork of Uniswap in 2020. In that sense a fork shares a codebase but has its own separate blockchain or contracts from the start.
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