Is hard fork backward-compatible?

A hard fork is a radical upgrade that can make previous transactions and blocks either valid or invalid and requires all validators in a network to upgrade to a newer version. It’s not backward-compatible .

technology, hard fork or (hardfork) refers to a radical change to the protocols of a blockchain network. In simple terms, a hard fork splits a single cryptocurrency into two and results in the validation of blocks and transactions that were previously invalid, or vice-versa .

When people hear about smart contracts, they often think about Ethereum. However, Ethereum is not the only blockchain platform that allows users to run smart contracts and create decentralized applications (DApps).