Atoms emit discrete frequencies of light due to their quantized electronic energy levels, which dictate the specific positions of electrons. These energy levels arise from quantum mechanics, particularly illustrated by Niels Bohr's model of the hydrogen atom, which, despite being outdated, effectively introduces the concept of energy quantization. Different atoms possess unique sets of energy levels, leading to the emission of distinct light frequencies when electrons transition between these levels. Understanding these principles is essential for grasping atomic behavior and spectral lines. The study of these discrete energy states is fundamental in fields such as spectroscopy and quantum physics.