Irrationality refers to actions or thoughts that are not based on logical reasoning or sound judgment. It often occurs when emotions, biases, or social pressures influence decision-making, leading individuals to make choices that contradict their best interests or available evidence. This concept is studied in various fields, including psychology and economics, where it helps explain behaviors that deviate from traditional models of rational decision-making. For example, people may engage in gambling despite knowing the odds are against them, illustrating how cognitive biases can lead to seemingly illogical choices.