An emission spectrum refers to the collection of wavelengths or frequencies of electromagnetic radiation emitted by atoms, molecules, or substances when they transition from higher to lower energy states. This emitted radiation is specific to the element or compound and provides characteristic patterns of spectral lines or bands unique to that substance. Each element or compound has its distinct emission spectrum, comprising lines or bands at specific wavelengths or frequencies corresponding to the energy differences between its quantized energy states. For instance, in atomic emission spectra, discrete lines represent transitions of electrons between atomic energy levels, while molecular emission spectra display more complex patterns due to molecular energy levels. Analyzing emission spectra is fundamental in fields like astronomy, chemistry, and physics.