Tuner may refer to someone or something which adjusts or configures a mechanical, electronic, or musical device.
Car tuning is modification of the performance or appearance of a vehicle. For actual "tuning" in the sense of automobiles or vehicles, see engine tuning. Most vehicles leave the factory set up for an average driver's expectations and conditions. Tuning, on the other hand, has become a way to personalize the characteristics of a vehicle to the owner's preference. Cars may be altered to provide better fuel economy, produce more power, or to provide better handling.
Car tuning is related to auto racing, although most performance cars never compete. Tuned cars are built for the pleasure of owning and driving. Exterior modifications include changing the aerodynamic characteristics of the vehicle via side skirts, front and rear bumpers, spoilers, splitters, air vents and light weight wheels.
Cars have always been subject to after-market modification. The golden age of car tuning was the decades between World War II and the beginning of air pollution restrictions. Both moderate and radical modification have been commemorated in the popular songs Hot Rod Race and Hot Rod Lincoln. The names of Abarth and Cooper appear on models styled after the cars they modified. Cosworth went, with support from Ford, from modifying English Ford Flathead engines for Lotus Sevens to dominating Formula One.
A tuner is a subsystem that receives radio frequency (RF) transmissions like radio broadcasts and converts the selected carrier frequency and its associated bandwidth into a fixed frequency that is suitable for further processing, usually because a lower frequency is used on the output. Broadcast FM/AM transmissions usually feed this intermediate frequency (IF) directly into a demodulator that convert the radio signal into audio-frequency signals that can be fed into an amplifier to drive a loudspeaker. More complex transmissions like PAL/NTSC (TV), DAB (digital radio), DVB-T/DVB-S/DVB-C (digital TV) etc. uses a wider frequency bandwidth, often with several subcarriers. These are transmitted inside the receiver as an intermediate frequency (IF). The next step is usually either to process subcarriers like real radio transmissions or to sample the whole bandwidth with A/D at a rate faster than the nyquist rate that is at least 2 times the IF frequency.
The term tuner can also refer to a radio receiver or standalone audio component that are part of an audio system, to be connected to a separate amplifier. The verb "tuning" in radio contexts means adjusting the radio receiver to receive the desired radio signal carrier frequency that a particular radio station uses.