What is quantization of energy?

The term "quantization of energy" describes the fact that, at subatomic scales, energy is best understood as existing in discrete "packets" known as photons, which are classified according to their denominations, much like paper money.

Money is thus quantized; it only comes in discrete amounts. For example, you can buy things with a one dollar bill or a five dollar bill, but there are no three dollar bills.

Photons are energy packages that, in quantum physics, are associated with various colors in the spectrum or forms of electromagnetic radiation, such as microwaves, radio waves, X-rays, and so on.

Each photon contains a distinct amount of discrete energy; a red photon has a specific energy value that is different from a blue photon. As a result, the red and blue photons are "quantized" in the same way that dollar bill denominations are.

More precisely, Plank's constant, which defines "how quantized" energy can get, is related to the uniqueness, or "quantization," of energy.

Quantization of energy is a concept in quantum mechanics that states that energy is not continuous but exists in discrete, quantized levels. According to this principle, energy can only take on specific, distinct values rather than any value within a continuous range. This idea is central to understanding phenomena such as the behavior of electrons in atoms, where energy levels are quantized and defined by specific quantum numbers.