Effect refers to a broad category of audio treatments applied to a signal to fundamentally change, enhance, or manipulate its character for creative purposes. While the line between "processing" (like EQ and compression) and "effects" can be blurry, the term is most commonly associated with time-based and modulation processors. These include reverb, delay, chorus, flanging, and distortion. In a mixing context, effects are often handled via "Auxiliary Sends" (allowing multiple instruments to share the same reverb) rather than "Inserts," enabling the engineer to blend the original "dry" signal with the processed "wet" signal to achieve the desired balance.