The number "6.626 × 10^-34" is known as Planck's constant, a fundamental constant in physics. It represents the smallest action in quantum mechanics and is crucial for understanding the behavior of particles at the atomic and subatomic levels. Planck's constant is used in the equation that relates energy to frequency, showing how energy is quantized. This means that energy can only exist in discrete amounts, which is a key concept in quantum theory. Its small value indicates that quantum effects are significant only at very small scales, such as those of atoms and photons.