Fluorescent proteins are intimately connected to research in the life sciences. Tagging of gene products with fluorescent proteins has revolutionized all areas of biosciences, ranging from fundamental biochemistry to clinical oncology, to environmental research. The discovery of the Green Fluorescent Protein, its first, seminal application and the ingenious development of a broad palette of fluorescence proteins of other colours, was consequently recognised with the Nobel Prize for Chemistry in 2008.   Fluorescent Proteins I is devoted to the basic photophysical and photochemical aspects of fluorescent protein technology. Experienced experts highlight colour tuning, the exploration of switching phenomena and respective methods for their investigation. The book provides a thorough understanding of primary molecular processes allowing the design of fluorescent proteins for specific applications.