In real-world economic situations, the decision-making processes of economic agents are heavily influenced by the presence of risk and uncertainty. Unlike idealized conditions where outcomes are predictable and certain, agents often operate in environments where the consequences of their choices are uncertain and span a spectrum of possible outcomes. This inherent unpredictability makes it challenging to assess the full implications of any given decision. This chapter seeks to provide a comprehensive yet concise exploration of the fundamental principles governing individual decision-making under uncertainty.