A sector is a distinct part or division of something larger, like slicing a pie into separate pieces. In business and economics, we talk about different sectors of the economy: the technology sector includes companies like Apple and Microsoft, the healthcare sector includes hospitals and drug makers, and the agricultural sector includes farms and food production. Each sector groups together organizations doing similar kinds of work.

In geometry, a sector is the wedge-shaped slice you get when you draw two lines from the center of a circle outward, like a single slice of pizza. This geometric meaning helps explain how we use the word in other ways.

You'll also hear sector in other contexts. A city might be divided into sectors for emergency services, so firefighters know which sector they're responsible for. In science fiction, space is often divided into sectors to help with navigation. Military organizations divide areas into sectors for organizing patrols or operations.

The key idea is always the same: taking something large and complex, then dividing it into manageable, organized parts that each have their own identity and purpose.