Quantization is a fundamental concept in quantum mechanics that refers to the idea that certain physical quantities, such as energy, momentum, and angular momentum, can only take on discrete, quantized values rather than continuous ones.

In classical physics, it's often assumed that these quantities can vary continuously over a range of values. For example, the energy of a particle in classical physics can theoretically take on any value within a certain range. However, in quantum mechanics, certain properties are quantized, meaning they can only exist in specific, discrete increments.

One of the most famous examples of quantization is seen in the energy levels of electrons in an atom. According to quantum mechanics, electrons can only occupy specific energy levels within an atom, and the energy difference between these levels is quantized. When an electron transitions between energy levels, it must absorb or emit a discrete amount of energy, corresponding to the difference between the initial and final energy levels.

Similarly, other physical quantities such as momentum and angular momentum also exhibit quantization in quantum mechanics. For example, the angular momentum of an electron in an atom is quantized and can only take on certain discrete values, dictated by the principles of quantum mechanics.

Quantization has profound implications for our understanding of the behavior of matter and energy at the microscopic scale. It is a central concept in quantum theory and underlies many phenomena observed in quantum systems, including the discrete spectral lines in atomic spectra, the stability of matter, and the behavior of particles in quantum field theory.