A fork is like a family squabble that splits the dinner table into two (or more) groups. In blockchain terms, a hard fork changes the rules so older nodes cannot validate the new blocks, potentially creating a permanent chain split. A soft fork, meanwhile, tightens existing rules and remains compatible with non-upgraded nodes (they’ll still see new blocks as valid). Notable Bitcoin forks include Bitcoin Cash (a hard fork in 2017) and SegWit activation (a soft fork in 2017). If consensus isn’t achieved, separate ‘forked’ networks can persist, leaving users holding coins on each chain.