Forks: Hard Forks vs Soft Forks

What you’ll learn

• •A fork is a change to a blockchain's rules; because no central authority can impose it, enough of the network has to voluntarily adopt it.
• •A soft fork is backward-compatible — old software still recognises new blocks as valid, so the chain doesn't split.
• •A hard fork is not backward-compatible — if the network doesn't upgrade together, it can permanently split into two separate chains.
• •Bitcoin Cash (2017) split from Bitcoin over a disagreement about block size and how to scale transaction capacity.
• •Most Bitcoin protocol upgrades throughout its history have been soft forks, passing without splitting the network.
• •After a genuine chain split, holders typically end up with a balance on both resulting chains, since history is shared up to the split point.