Time Loop

A time loop or temporal loop is a common plot device in science fiction (especially in universes where time travel is commonplace) in which time runs normally for a set period (usually a day or a few hours) but then skips back like a broken record. When the time loop "resets", the memories of most characters are reset (i.e. they forget all that happened). The plot is advanced by having one or more central characters retain their memory or become aware of the loop through déjà vu.

One well-known example of this is in the 1993 film Groundhog Day, in which the main character is the only one aware of the time loop. Stories with time loops commonly center on correcting past mistakes or on getting a character to recognize some key truth; escape from the loop may then follow.