Imagine you’re sorting emails into “spam” and “not spam.” You scan each message for clues—certain words, the sender’s address, the time it arrived—and then make a yes-or-no call. That’s classification: the skill of putting items into distinct groups based on their features. In this chapter, you’ll learn five powerful families of classification methods, from simple rules that draw a single dividing line to networks that mimic the brain. Each approach has its own personality, and together they form the core toolkit for making smart, automated decisions from data.