How it works
The blockchain’s rules are encoded in node software. When developers propose new rules, node operators decide whether to upgrade. A soft fork tightens the rules so old nodes accept the new chain but cannot produce blocks on it. A hard fork loosens or changes rules in a way old nodes reject; the chain splits into two if a meaningful share of operators refuse to upgrade.
Example
Bitcoin Cash forked from Bitcoin in August 2017 as a hard fork over block-size limits. Two separate chains exist today, both descending from the same history before the split. Ethereum and Ethereum Classic split in 2016 after a hard fork rolled back transactions affected by the DAO hack. Soft forks are usually less dramatic: SegWit on Bitcoin in 2017 enabled new features without splitting the chain.
Why it matters
Forks are how decentralised protocols evolve. They also redistribute economic stake: holders of the pre-fork coin receive equal balances on both post-fork chains. Major forks can be either upgrades the community broadly accepts or contentious splits that fragment value and community. When holding through a fork, check that your wallet or exchange supports both new chains; some only credit one side, costing holders the airdropped half.
