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.

• In mathematics (geometry), a sector is the "pie shaped" area of part of a circle 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 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. Diagram of a sector (part of a circle) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Mathematics is the study of quantity, structure, space and change. ... Geometry (from the Greek words Geo = earth and metro = measure) is the branch of mathematics first popularized in ancient Greek culture by Thales (circa 624-547 BC) dealing with spatial relationships. ... In Euclidean geometry, a circle is the set of all points in a plane at a fixed distance, called the radius, from a fixed point, called the centre. ... RADIUS (Remote Authentication Dial In User Service) is an Authentication, Authorization and Accounting (AAA) protocol for applications such as network access or IP mobility. ... The word quadrant can mean: A region of the Cartesian coordinate plane with a specific sign for the x and y coordinates: (+, +), (-, +), (-, -) or (-, +). It is the 2-dimensional case of an Orthant (based on the above) One of the four divisions of the city layout of Washington, D.C. and... Can refer to a region of Euclidean 3-space with a specific sign for x, y and z coordinates. ... The tower of a personal computer (specifically a Power Mac G5). ... Hardware is equipment such as fasteners, keys, locks, hinges, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts, especially when they are made of metal. ... The word track can mean more than one thing. ... Typical hard drives of the mid-1990s. ... In computing, sound reproduction, and video, an optical disc is flat, circular, usually polycarbonate disc whereon data is stored. ... In computer engineering, hard disk drive partitioning is the creation of logical divisions upon a hard disk that allows one to apply operating system-specific logical formatting. ... File Allocation Table (FAT) is a file system that was developed for MS-DOS and used in consumer versions of Microsoft Windows up to and including Windows Me. ... Economics (deriving from the Greek words οίκω [okos], house, and νέμω [nemo], rules hence household management) is the social science that studies the allocation of scarce resources to satisfy unlimited wants. ... The private sector of a nations economy consists of those entities which are not controlled by the state - i. ... The public sector is that part of economic and administrative life that deals with the delivery of goods and services by and for the government, whether national, regional or local/municipal. ... The tertiary sector of industry, also called the service sector or the service industry, is one of the three main industrial categories of a developed economy, the others being the secondary industry (manufacturing and primary goods production such as agriculture), and primary industry (extraction such as mining and fishing). ... The secondary sector of industry is the manufacturing sector of industry. ... The primary sector of industry generally involves the conversion of natural resources into primary products. ... The secondary sector of industry is the manufacturing sector of industry. ... The tertiary sector of industry, also called the service sector or the service industry, is one of the three main industrial categories of a developed economy, the others being the secondary industry (manufacturing and primary goods production such as agriculture), and primary industry (extraction such as mining and fishing). ... Formula One, abbreviated to F1 and also known as Grand Prix racing, is the highest class of single-seat open-wheel auto racing. ...