(Wikipedia excerpt: ..”..A resistor/s (R) is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, (R) are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power (R) that can dissipate many watts of electrical power as heat may be used as part of motor controls, in power distribution systems, or as test loads for generators.
Fixed (R) have resistances that only change slightly with temperature, time or operating voltage. Variable (R) can be used to adjust circuit elements (such as a volume control or a lamp dimmer), or as sensing devices for heat, light, humidity, force, or chemical activity. (R) are common elements of electrical networks and electronic circuits and are ubiquitous in electronic equipment. Practical (R) as discrete components can be composed of various compounds and forms. (R) are also implemented within integrated circuits. ..“…)