Nostalgia is a self-relevant emotion that often involves interactions with close others or significant life events. It is typically associated with positive affect, though it can also involve negative emotions. Studies show that nostalgic experiences often involve a redemption sequence, where negative events are followed by positive ones. Nostalgia is triggered by negative mood and loneliness, and it serves to strengthen social bonds, increase positive self-regard, and generate positive affect. The term "nostalgia" originated from a medical theory in the 17th century, but it has since been redefined as a psychological concept. Recent research has shown that nostalgia is a common experience, with many people experiencing it regularly. It is often triggered by negative emotions and social interactions, and it plays a functional role in enhancing social connections and self-esteem. The studies reviewed provide a comprehensive understanding of the content, triggers, and functions of nostalgia, highlighting its significance in human experience.Nostalgia is a self-relevant emotion that often involves interactions with close others or significant life events. It is typically associated with positive affect, though it can also involve negative emotions. Studies show that nostalgic experiences often involve a redemption sequence, where negative events are followed by positive ones. Nostalgia is triggered by negative mood and loneliness, and it serves to strengthen social bonds, increase positive self-regard, and generate positive affect. The term "nostalgia" originated from a medical theory in the 17th century, but it has since been redefined as a psychological concept. Recent research has shown that nostalgia is a common experience, with many people experiencing it regularly. It is often triggered by negative emotions and social interactions, and it plays a functional role in enhancing social connections and self-esteem. The studies reviewed provide a comprehensive understanding of the content, triggers, and functions of nostalgia, highlighting its significance in human experience.