A checklist is a type of job aid used in repetitive tasks to reduce failure by compensating for potential limits of human memory and attention. Checklists are used both to ensure that safety-critical system preparations are carried out completely and in the correct order, and in less critical applications to ensure that no step is left out of a procedure. they help to ensure consistency and completeness in carrying out a task. A basic example is the "to do list". A more advanced checklist would be a schedule, which lays out tasks to be done according to time of day or other factors, or a pre-flight checklist for an airliner, which should ensure a safe take-off.

A primary function of a checklist is documentation of the task and auditing against the documentation. Use of a well designed checklist can reduce any tendency to avoid, omit or neglect important steps in any task. For efficiency and acceptance, the checklist should easily readable, include only necessary checks, and be as short as reasonably practicable.