Electronic component that accepts a low-level signal and recreates the signal with more power; this term is most often used in audio/video to describe an audio component which takes in line-level audio signals through interconnect cables and outputs a high-powered replica of the input in order to drive speakers and create sound. The signals sent over interconnect cables through an audio/video system between system components carry the same signal as amplifier outputs just in a low-power form. If the output of a pre-amplifier were given directly to a speaker, the signal would not be strong enough to create movement of the voice coil and thus create sound. The amplifier takes in the signal and ups its power so that the speaker’s voice coil will be sufficiently excited to generate movement and thus sound.

Think of a man and a forklift. The man tries to lift a two-ton box with his arms, but he doesn’t have enough power. Instead, he puts his input into the forklift, which turns that input into a strong output capable of lifting the heavy box. In both instances the desire, the signal, is the same. The forklift is simply an amplifier enabling the original action to do more work. An audio amplifier works the same way putting out the power to move the speaker drivers but all the time mirroring the low-power input signal.