Anna is a student at the School of Economics, studying microeconomics and other exciting subjects. She is a sensible person, with a part-time job at a grocery shop and good control over her finances. Sitting in the study hall, Anna is thinking carefully about how much to spend on housing and on other things that bring her joy, such as exercise, food, and entertainment. Inspired by her microeconomics course, Anna often finds herself thinking about what the people around her spend their money on—for example, what customers at the shop have in their shopping baskets. It’s especially interesting when a product is on offer: how does that affect shopping behaviour? This chapter is about consumer choice. A basic assumption in microeconomic theory is that people do the best they can with the money they have, given market prices. Consumer theory is built around three key components: income, prices, and preferences. We begin by examining the consumer’s set of options and how changes in prices and income affect these possibilities. We then turn to preferences and introduce the concept of utility, showing how the consumer can use their income to maximise utility. Finally, we consider how changes in prices and income influence consumer choice.