Planck's Contribution

As shown in Ideas to Implementation, Planck made a great contribution to the understanding of energy in quantum states. In the extremely small world of atoms and energy, the classical model was not able to predict the nature of black body radiation.
The UV catastrophe was resolved as Planck theorised the quantum nature of energy. He believed atomic oscillators acted like antenna that received and emitted radiation in discrete amounts called 'packets' of radiation.

Planck tried to use a statistical method of treating the problem by breaking the energy into smaller parts which then would be intergrated and added up to produce continuity. In doing so however he realised that the method he employed (Boltzmann's equations) simply tended towards infinity ridiculously. Planck found that he did not need to complete the statistical treatment of adding up all the energy packets but rather left the equation 'incomplete' but resolved the problem.

Planck realised that this described the atomic oscillators as sensitive to only certain frequencies of oscillations giving rise to his equation:

$E=hf$