Sector

A sector is a part of a whole. As a well the specific usages below, it can also be used metaphorically, referring to a generic piece or portion of something.

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• In Euclidean plane geometry, a sector is a "pie-shaped" part of a disk enclosed by two radii and an arc. In the special case of the circle being divided into 4 equal sectors, they are called quadrants; divided into 8 equal sectors, they are called octants.
• In the context of computer hardware, a sector is a sub-division of a track of a magnetic hard disk or optical disc. A sector stores a fixed amount of data. The typical formatting of sectors allows holding 512 bytes (e.g. harddisks and diskettes) or 2048 bytes (e.g. optical discs) of data. (See also Cylinder-head-sector, hard disk drive partitioning, FAT.)
• In economics, economic activity is often categorised into sectors, in a variety of schemes. For example private sector vs public sector; service sector vs manufacturing sector; primary sector/secondary sector/tertiary sector.
• In Formula 1, a sector is part of the track. There are usually 2 or 3 sectors on a track.