The history of fluorescence is closely connected to natural products. The first documented observation occurred in 1565 when a natural extract, used as a medicinal infusion for treating urinary tract infections, was noted for its distinctive “blue colour”, later revealed to be fluorescence emission. This discovery is also connected to the conquest of the Americas and the traditions passed from Mexican natives to the Spaniards. In this chapter, we begin by exploring the main significant events in the history of fluorescence. We then focus on the history and evolution of chlorophyll fluorescence, whose analysis and interpretation are central to the book’s theme. It is an engaging journey that illustrates how early researchers’ insightful observations of luminous phenomena with the naked eye enabled the way for developing innovative methods to analyze chlorophyll fluorescence and its relationship to the photosynthetic process. These methods evolved from studying individual leaves to entire canopies and even remote observations via satellite monitoring of vegetation.