A hi-fi component is an electronic device used to improve the sound quality of audio equipment. The four components that make up a hi-fi system are preamp, STEREO, amp, and TUNER. Preamp is a short form of preamplifier, which is an electronic device used to amplify a weak signal before it is sent to the amplifier. STEREO is short for stereophonic, which is a type of sound reproduction that creates an illusion of directionality and depth. Amp is short for amplifier, which is an electronic device used to increase the power of a signal. TUNER is short for radio TUNER, which is an electronic device used to receive radio signals. Together, these four components make up a hi-fi system, which is used to improve the sound quality of audio equipment.