What Is a Fork?
A fork is a change to a blockchain's rules, and sometimes a divorce over them. Because nobody owns the network, upgrades happen by nodes choosing which software to run; when they disagree enduringly, one chain becomes two, both carrying the same history up to the split.
How It Actually Works
- Soft forks tighten rules backward-compatibly; old nodes still follow along. Bitcoin upgrades like SegWit and Taproot took this path.
- Hard forks change rules incompatibly: everyone must upgrade, or the chain splits. Ethereum hard-forks routinely and cooperatively as its upgrade process.
- Contentious splits are the dramatic case: Bitcoin vs. Bitcoin Cash in 2017 over block size, Ethereum vs. Ethereum Classic in 2016 over reversing the DAO hack. Markets then price which side keeps the economic gravity, and the answers were emphatic both times.
- Holders at a split typically end up with coins on both chains, which is where fork-airdrop tax questions come from: my tax guide covers the IRS treatment.
Risks and Common Mistakes
- Fork-claiming scams: "claim your forked coins" sites harvesting seed phrases outnumber legitimate claims enormously. The phrase never goes anywhere, forks included.
- Replay confusion in the raw aftermath of splits, when transactions can echo across both chains without proper protection. Waiting out the chaos costs nothing.
- Buying "the cheap version" of a major coin on ticker resemblance. The market's verdict between fork siblings has historically been loud and durable.
When It Matters
Understanding upgrade headlines, why multiple coins share a name and a history, and what governance-without-governors actually looks like when tested. The fundamentals foundation lives on my Fundamentals page.
Related Terms
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