A flashback is a narrative technique used in literature and film that interrupts the chronological flow of a story to revisit a past event. This device allows the audience to gain deeper insight into a character's background, motivations, or emotions. Flashbacks can be triggered by various stimuli, such as a sound, smell, or visual cue, and often provide context that enhances the main storyline. In psychology, flashbacks can also refer to a sudden, vivid recollection of a traumatic event, often experienced by individuals with conditions like Post-Traumatic Stress Disorder (PTSD). These involuntary memories can be distressing and may cause the person to relive the experience as if it were happening in the present. Understanding both literary and psychological flashbacks helps in grasping their significance in storytelling and mental health.