This chapter starts with the notions of “objective reality” and “subjective reality.” Objectivity attempts to represent the outside world without bias or presuppositions, while subjectivity results from personal cognition or preferences. The chapter discusses the mechanisms by which people make choices. Research conducted in the last 60 years has resulted in a shift in our understanding of human decision making from the concept of rationality to a new model that acknowledges the role of cognitive biases. Individual choices and preferences are aggregated to form social preferences, and this chapter reviews some techniques behind this aggregation. It also explains that preference ranking does not always imply a unique result because it is possible to get a cyclic pathway, as in the rock, paper, scissors game. Elements of this game appeared in both ancient religious systems and in the US governmental system. Then the chapter turns to the famous PageRank algorithm, which made Google what it is today. The algorithm is able to produce a relevant ranking of websites within a very reasonable time. The algorithm could produce different results, and rank reversal may happen in real-world situations. Ranking many elements based on some characteristic features, such as words based on the frequency of their occurrence, can use statistical methods. In many real cases, the distribution of these features strongly deviates from the bell curve, and models instead a skew distribution, technically called a power law distribution.