Undeniably, the discovery of the first computer could be recognized as one of the most breakthrough events in the last century. These machines completely revolutionized the science and industry. It is due to not only the extreme increase in the speed of calculations but also the emergence of the entirely new methods for studies. Examples of the latter are the computer simulations, which nowadays are commonly applied to model behaviors of many physical, chemical, biological, meteorological, as well as human systems. The scientific importance of the above method results from the fact that it links experimental results with the theoretical predictions. The findings obtained from computer simulations of model systems are compared with the experimental results to verify the correctness of the models. On the other hand, use of certain approximations enables the theoretical solution of the model systems, yielding the results, which are subsequently compared with findings of computer simulations verifying the validity of applied approximations. Thus the computer simulations are recognized as an inherent part of the modern research.