To categorize means to sort things into groups based on what they have in common. When you categorize your books, you might put all the mysteries on one shelf, the science books on another, and the fantasy novels on a third. When a librarian categorizes new arrivals, she's deciding where each book belongs so people can find what they're looking for.

Your brain categorizes information constantly. When you meet a new animal, you quickly categorize it: Is it a mammal or a reptile? Is it dangerous or friendly? This automatic sorting helps you make sense of the world. Scientists categorize plants and animals into kingdoms, families, and species. Teachers categorize assignments as homework, classwork, or tests.

When you categorize, you're creating or using categories to organize things that would otherwise be jumbled together. A store categorizes products by type. A museum categorizes artifacts by time period or culture.

Sometimes categorizing is straightforward: forks go with forks, spoons with spoons. But sometimes it's tricky. Is a tomato a fruit or a vegetable? How you categorize something can depend on your purpose. Botanists categorize tomatoes as fruits, but cooks categorize them as vegetables. The categories you choose and how you use them can shape how you understand and work with information.