Here's why:

* Excited state: An electron in an atom is in an excited state when it occupies an energy level higher than its ground state. This occurs when the atom absorbs energy (like from light or heat).

* Ground state: The ground state is the lowest energy level an electron can occupy within an atom.

* Energy release: To return to the ground state, the electron must release the excess energy it gained. This energy is typically released as a photon of light, causing the atom to emit light.

In summary: The transition from an excited state to the ground state is an energy-releasing process, always accompanied by the emission of energy, usually in the form of light.