A processor in the world of guitar effects refers to a multi-effects or digital unit that can manipulate sound in multiple ways using digital signal processing (DSP). These devices offer a wide range of effects—such as reverb, delay, chorus, distortion, and amp modelling—often in a single unit, making them a versatile tool for musicians who want a compact and powerful solution for shaping their tone.

Processors can range from floor-based multi-effects pedals, like the Line 6 Helix or Boss GT-1000, to rack-mounted units used in professional studios and live setups. They often include presets, MIDI control, and USB connectivity for deep customisation, making them ideal for guitarists looking for a flexible, all-in-one effects system without the need for multiple standalone pedals.