Fader
The slider that sets a channel's level in a mix, and which DAWs still draw on screen out of sheer habit.
On a mixing console every channel ends in a fader. The scale is logarithmic and marked in decibels, with 0 dB — unity gain, no change — placed a little below the top to leave room for boost. A long throw, 100 mm being the studio norm, gives finer control than a rotary knob, and ten fingers can ride ten channels at once.
Motorised faders move themselves when automation plays back and yield when a hand grabs them. On analogue desks the fader often doesn't touch the audio at all but drives a VCA, which makes channel grouping possible. In software the slider survives as a drawing and on control surfaces, because no mouse beats a physical fader for a slow fade-out.