This interdisciplinary book gives a comprehensive survey of the state-of-the-art: from applications and trends in fluorescence techniques in science to medicine and engineering. Written for practitioners and researchers in industry and academia, it covers fields like environmental and materials science, biology, medicine, physics and chemistry. Moreover, it reports on such new and breathtaking methods as ultra-fast time-resolved or single molecule spectroscopy, gives examples of applications in the fields of electroluminescent polymers, visualization of membrane potentials in neurons and fluorescence imaging of the brain.