Question

What is a hard fork?

Answer 1

A hard fork is a permanent divergence in the blockchain, commonly occurring when non-upgraded nodes can't validate blocks created by upgraded nodes. It results in a split where one path follows the new version of the blockchain, while the other continues along the old path.

Answer 2

A hard fork is a radical change to the protocol of a blockchain network that makes previously invalid blocks or transactions valid, and vice versa. This requires all nodes or users to upgrade to the latest version of the protocol software. It is essentially a divergence in the blockchain, resulting in two separate chains with a shared history up to a certain point.