Traditional economics portrays decision making as rational deliberation that computes optimal choices based on well-defined objectives and perfect information. In reality, limited information and cognition as well as certain features of the human psychology often result in decisions that deviate from this assumption. Behavioural economics attempts to explain these deviations using insights and theories from the other social sciences, in particular psychology. This subject introduces students to this intersection of economics and psychology. Its aim is not to be mathematically or theoretically thorough. Rather, it focuses on developing a better understanding of how human psychology affects economic decisions and how such knowledge can be applied to real world business and policy issues, including to nudge.