Thermal stability of magnetic recording is of great importance. This dissertation discusses the major theories and simulation techniques currently in use. Simulations using a Langevin approach are conducted to examine the thermal decay of ensembles of non-interacting particles with both coherent and non-coherent magnetization. This decay is compared to the simplified model of exponential decay. Understanding the magnetization relaxation process is of importance when trying to understand the reversal of the magnetization within materials. This process becomes increasingly important as data rates increase. Simulations will be conducted that do not assume a phenomenological damping. Instead, it will be seen how the relaxation process begins by dissipating energy to magnetostatic and exchange coupled excitations. A model incorporating damping to lattice vibrations by magnetostriction will also be presented. During the relaxation process energy flows from the magnetic system to the lattice. Results of simulations are compared to the damping obtained via a phenomenological approach.