Explain the importance and the main postulates of Planck's quantum theory.

(N/A) Planck's quantum theory was proposed to explain phenomena like black body radiation and the photoelectric effect,which could not be explained by the wave theory of light.
Postulates:
$1$. Atoms and molecules emit or absorb energy in discrete quantities called 'quanta' rather than in a continuous manner.
$2$. The energy $(E)$ of a quantum of radiation is directly proportional to its frequency $(v)$,expressed as $E \propto v$ or $E = hv$,where $h$ is Planck's constant $(6.626 \times 10^{-34} \ J \ s)$.
$3$. The total energy emitted or absorbed by a body is an integral multiple of a quantum,given by $E = nhv$,where $n = 1, 2, 3, \dots$.
Importance:
Planck's theory successfully explained the distribution of intensity in the radiation from a black body as a function of frequency or wavelength at different temperatures,which classical physics failed to do.