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Nongeometric duration distributions occur in many familiar areas, such as the length of spoken words in phone conversation, as well as other areas in voice recognition. Although the Gaussian distribution occurs in many scientific fields (an observed embodiment of the LLN, among other things), there are a huge number of significant (observed) skewed distributions, such as heavy‐tailed (or long‐tailed) distributions, multimodal distributions, etc.

Heavy‐tailed distributions are widespread in describing phenomena across the sciences. The log‐normal and Pareto distributions are heavy‐tailed distributions that are almost as common as the normal and geometric distributions in descriptions of physical phenomena or man‐made phenomena. Pareto distribution was originally used to describe the allocation of wealth of the society, known as the famous 80–20 rule, namely, about 80% of the wealth was owned by a small amount of people, while “the tail,” the large part of people only have the rest 20% wealth. Pareto distribution has been extended to many other areas. For example, internet file‐size traffic is a long‐tailed distribution, that is, there are a few large sized files and many small sized files to be transferred. This distribution assumption is an important factor that must be considered to design a robust and reliable network and Pareto distribution could be a suitable choice to model such traffic. (Internet applications have many other heavy‐tailed distribution phenomena.) Pareto distributions can also be found in a lot of other fields, such as economics.