Fork (concept)

In plain words

A fork is the chain splitting in two. Most are accidents: two miners find a block at the same moment, the network briefly sees two histories, and the next block settles it. The losing branch is abandoned. Rule forks are different: if some nodes change the rules and others refuse, the chain splits permanently — two networks, two coins. Nobody can stop a fork. Nobody has to follow one either. You follow the rules your node enforces.

Why it matters

• Accidental forks heal in minutes: the next block picks a winner.
• Rule disputes that won't resolve become permanent splits — two coins, judged by the market.
• Your node's rules decide which chain counts as Bitcoin for you.

Not to be confused with

• Software fork — copying code to start a new project. A chain fork splits history itself.

Go deeper

• Soft fork
• Hard fork
• Orphan & stale blocks