Retro style is imitative or consciously derivative of lifestyles, trends, or art forms from history, including in music, modes, fashions, or attitudes. In popular culture, the "nostalgia cycle" is typically for the two decades that begin 20–30 years ago.

Nostalgia is a sentimentality for the past, typically for a period or place with happy personal associations. The word nostalgia is a learned formation of a Greek compound, consisting of νόστος (nóstos), meaning "homecoming", a Homeric word, and ἄλγος (álgos), meaning "sorrow" or "despair", and was coined by a 17th-century medical student to describe the anxieties displayed by Swiss mercenaries fighting away from home. Described as a medical condition—a form of melancholy—in the early modern period, it became an important trope in Romanticism.