sector

Sector is a term with several related but distinct meanings in geometry, economics, geography, and information technology. In geometry, a circular sector is the region bounded by two radii and the arc between them. The central angle subtending the arc defines the size of the sector. The area of a circular sector is (1/2) r^2 θ when θ is in radians, and the arc length is r θ; in degrees, the area is (θ/360) π r^2 and the arc length is (θ/360) 2π r.

In economics and business, a sector denotes a broad subset of the economy that shares similar activities, products, or services. Common classifications distinguish sectors such as primary (extraction), secondary (manufacturing), and tertiary (services); some frameworks add quaternary and quinary sectors. Sectoral analysis studies how different sectors contribute to growth, employment, and policy outcomes, and indicators such as output, value added, and productivity are used to track sector performance.

In geography and urban planning, a sector can refer to a division of a city or region for administrative or planning purposes, often defined along radial lines from a central point. In computing, a sector is a fixed-size unit of data on storage media and the smallest addressable unit by the disk controller. Modern disks commonly use 4,096-byte sectors, while older formats used 512-byte sectors.

The word sector derives from Latin sector, meaning a cut or partition.