This course is an introductory course in economics where we study the decision making of individual actors (consumers, employees, firms, governments, etc.) in an economy. Actors must make decisions about behaviours because they face scarce resources, but often they find that trading with other actors in markets can increase the wellbeing of all parties. This course models and examines the nature of these interactions, highlighting when they work well and when they fail to increase wellbeing and what might be the solution to these failures. We hope that the guide gives you an idea of what you can expect from this course, and also what we expect from you as a participant on the course.