Imagine you are buying a new phone. There are dozens of models with different cameras, batteries, and prices. You do not open a spreadsheet and calculate the perfect trade-off for every option—you glance at a few, rule out the ones that seem too expensive or have poor reviews, and pick one that feels right. That is a heuristic in action. This chapter unpacks the mental shortcuts we all use to make decisions quickly and with less effort, and shows how these shortcuts shape our everyday choices.