Final answer:
An element gives off light through the process of emission of photons. When an element is excited, its electrons gain energy and as they return to their original energy levels, they release energy in the form of photons. Each element has its own unique characteristic line spectrum.
Step-by-step explanation:
The best explanation for how an element gives off light is through the process of emission of photons. When an element is excited, either by heating or by passing an electric current through it, its electrons gain energy and move to higher energy levels. As the electrons return to their original energy levels, they release energy in the form of photons, which we perceive as light. Each element has its own unique characteristic line spectrum, which is the specific set of colors emitted by that element.