checkpoint

A checkpoint is a designated point in a process where progress is verified, the state of a system is saved, or access is controlled. The term is used across domains to denote points where validation, recovery, or management actions occur.

In computing, checkpointing saves the state of a running program or system so it can be resumed after a failure. Checkpoints may record memory, processor state, and open files, and may be full or incremental. They support fault tolerance in high-performance computing, databases, and long-running jobs.

In biology, cell cycle checkpoints monitor conditions before a cell proceeds with division. Key checkpoints occur at the G1/S and G2/M transitions and during mitosis at the spindle assembly checkpoint. They assess DNA integrity and replication status and can pause, repair, or trigger cell death.

In security and transportation, a checkpoint is a controlled location where identities or belongings are inspected, such as border crossings, police stops, or facility screenings.

In video games, checkpoints mark progress and provide save points or respawn locations to reduce repetition. In software and machine learning, a checkpoint is a saved model or state used to resume training or evaluation.

See also: milestones, snapshots, and versioning.