This document discusses fluorescence spectroscopy. It defines fluorescence spectroscopy as a type of electromagnetic spectroscopy that analyzes fluorescence from a sample. It describes the basic principles of how fluorescence spectroscopy works, including how molecules are excited to higher energy states and then emit photons as they fall to lower energy states. It also outlines the key components of a fluorescence spectroscopy system, including light sources, wavelength selection tools, detectors, and read-out devices. Finally, it discusses some common applications of fluorescence spectroscopy and some limitations.