What Is ‘Transaction Finality’ and Why Is It Important against a 51 Percent Attack?

Transaction finality is the guarantee that a confirmed transaction cannot be reversed or altered. It is crucial against a 51 percent attack because an attacker's main goal is to reverse their own transactions to double-spend.

Once a transaction reaches finality, the cost to reverse it becomes prohibitively high, especially in PoS systems with slashing. High finality ensures trust and reliability in the blockchain's ledger, making the network resilient to manipulation.