Overview
A checkpoint is a point in a blockchain's history that is considered final, from which older blocks are not reverted. It provides a stronger finality guarantee than probabilistic confirmation. Checkpoints can be protocol-defined or social.
How It Works
In proof-of-stake systems, checkpoints occur when validators finalize a block, and reverting it would trigger slashing. Some networks rely on social or centralized checkpoints to protect against deep reorgs. They define a boundary of historical safety.
Why It Matters
Checkpoints give users and exchanges a clear point beyond which transactions are safely settled. They reduce the risk of expensive reorganization attacks. They are a key part of proof-of-stake finality design.
Related Concepts
Checkpoints relate to Finality, Attestations, and Slashing in Proof of Stake. They define irreversible history.