A sampler is an electronic musical instrument similar in some respects to a synthesizer, but instead of generating sounds, it uses recordings (or "samples") of sounds that are loaded or recorded into it by the user. These sounds are then played back by means of the sampler program itself, a keyboard, sequencer or another triggering device to perform or compose music. Because these samples are now usually stored in digital memory, the information can be quickly accessed. A single sample may often be pitch-shifted to produce musical scales and chords.