Atomic transitions refer to the process by which an electron in an atom moves between different energy levels or orbitals. When an electron absorbs energy, it can jump to a higher energy level, a state known as excitation. Conversely, when it loses energy, it falls back to a lower energy level, often releasing energy in the form of light or electromagnetic radiation. These transitions are fundamental to understanding various phenomena in physics and chemistry, including the emission spectra of elements. For example, the hydrogen atom exhibits distinct spectral lines due to its unique atomic transitions, which are crucial for identifying elements in stars and other celestial bodies.