The electronic equivalent of a piano's damper pedal. In most synthesizers, the sustain pedal latches the envelopes of any currently playing or subsequently played notes at their sustain levels, even if the keys are lifted.

A sustain or sustaining pedal (also damper pedal or loud pedal) is the most commonly-used pedal in a modern piano. It is typically the rightmost of two or three pedals. When pressed, the sustain pedal "sustains" all the strings on the piano, removing the dampers from all strings and allowing them to vibrate freely.