blockchain fork

A fork is what happens when a blockchain splits into two possible paths. Because the chain is just a single growing line of blocks, a fork is a fork in the road — a moment where two different versions of 'what comes next' exist at once. Some forks are momentary accidents the network quickly resolves; others are deliberate changes to the rules that can permanently divide a chain into two.

Temporary forks happen naturally. If two miners find a valid block at nearly the same time, parts of the network briefly see different tips of the chain. The protocol settles this automatically: whichever branch gets extended first becomes the accepted chain, and the orphaned block is discarded. This is just the network healing a brief disagreement, and it resolves within a block or two.

Deliberate forks are upgrades to the rules themselves, and they come in two flavors. A soft fork tightens the rules in a backward-compatible way, so nodes that have not upgraded still accept the new blocks — the network stays unified. A hard fork loosens or changes the rules so that old and new software no longer agree; if part of the community keeps running the old rules, the chain permanently splits into two separate networks with two separate coins, as happened when Bitcoin Cash split from Bitcoin.