Fork
Web3 / blockchain technology
A change to a blockchain protocol's rules that results in either a temporary divergence in the chain (soft fork) or a permanent split creating two separate chains (hard fork). A soft fork is backward-compatible, meaning nodes running old software can still follow the new rules, though they may not understand all new features—Bitcoin's SegWit was implemented as a soft fork. A hard fork is not backward-compatible; nodes must upgrade to continue participating, and if a significant minority refuses to upgrade, the chain splits permanently into two with separate coins—Ethereum Classic (ETC) is the original Ethereum chain that split from ETH after the DAO hack hard fork in 2016. The term 'fork' also colloquially refers to copying an open-source protocol's codebase to create a new project, as many DeFi protocols have been forked from Uniswap or Compound. Example: Bitcoin Cash (BCH) was created via a hard fork from Bitcoin (BTC) in August 2017, when a group of miners and developers disagreed with the SegWit scaling solution and implemented larger block sizes instead, creating two permanent chains from the common history. Why it matters for Web3: Forks are both the governance mechanism through which open-source blockchains evolve and the risk event that can destroy coordination value. Understanding fork dynamics is essential for holders, miners, and developers who need to navigate protocol upgrades.
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