FX (short for “effects”) refers to a broad range of audio processing units used to alter or enhance the sound of musical instruments, particularly guitars, basses, and keyboards. These effects can range from simple tone adjustments to more complex transformations of the sound, adding texture, depth, and character to the performance. Common types of FX include delay, reverb, overdrive, distortion, modulation, chorus, flanger, phaser, and wah.

FX can be used in various combinations to create unique sounds and atmospheres, and they are typically found in the form of pedals or rack-mounted units. Some musicians also use multi-effects processors, which combine several effects in a single unit for convenience and versatility. FX are essential in shaping a musician’s tone, helping to define their signature sound, whether it’s a subtle enhancement or a dramatic transformation.