The Moog synthesizer is a modular synthesizer invented by the American engineer Robert Moog in 1964. Moog's company, R. A. Moog Co., produced numerous models from 1965 to 1981, and again from 2014. It was the first commercial synthesizer and established the analog synthesizer concept.

Modular synthesizers are synthesizers composed of separate modules for different functions. The modules can be connected together by the user to create a patch. The outputs from the modules may include audio signals, analog control voltages, or digital signals for logic or timing conditions. Typical modules are voltage-controlled oscillators, voltage-controlled filters, voltage-controlled amplifiers and envelope generators.