An Envelope Generator is a tool used in music synthesis to shape the amplitude or other parameters of a sound over time. It typically consists of four stages: Attack, Decay, Sustain, and Release, often referred to as the ADSR envelope. This allows musicians to control how a sound evolves from the moment it is triggered until it fades away. Envelope generators are commonly found in synthesizers and samplers, helping to create dynamic sounds. By adjusting the ADSR settings, users can produce a wide range of effects, from sharp percussive sounds to smooth, sustained tones, enhancing the overall musical composition.