A checklist or checklist (checklist, in English) is a work aid tool designed to reduce errors caused by the potential limits of memory and attention in humans. It helps ensure consistency and completeness in completing a task.[1]​ A simple example of a checklist would be a to-do list. A more complex example would be a schedule, where the tasks to be performed are detailed depending on the schedule, day, or other factors.

A checklist typically has a paragraph of text for each task, with an empty square on the left. Once the task has been completed, the square is filled with a small check mark.

But the format depends on the sector of activity in which it is being used. In aviation, for example, the list consists of a system and an action divided by a dotted line. Checkmarks are not used in this area because lists are usually read aloud and are intended for reuse.

Over-reliance on checklists can compromise performance in time-critical situations, for example, in a medical emergency or airline emergency. In any case, they should not be a substitute for common sense. Intensive training, including memorization of checklists, can integrate their use with other more adaptive and flexible problem-solving techniques.