Block finality

Block finality is the guarantee that a block and its transactions are permanent and cannot be reverted, reached either probabilistically through confirmations or deterministically through a consensus checkpoint.

Proof-of-work chains offer probabilistic finality: each added block makes reversal exponentially less likely, so services wait a set number of confirmations. Proof-of-stake chains can reach deterministic finality when validators finalize a checkpoint, after which reversal would require slashing a supermajority. Knowing the finality model tells you how long to wait before crediting funds. When you query historical balances or logs at a finalized height through the archive RPC, the returned data is stable.