Operator is a software synthesizer

Software synthesizer

A software synthesizer, also known as a softsynth is a computer program or plug-in for digital audio generation. Computer software which can create sounds or music is not new, but advances in processing speed are allowing softsynths to accomplish the same tasks that previously required dedicated...

 included in Ableton Live

Ableton Live

Ableton Live is a loop-based software music sequencer and DAW for Mac OS and Windows by Ableton. The latest major release of Live, Version 8, was released in April 2009. In contrast to many other software sequencers, Live is designed to be an instrument for live performances as well as a tool for...

. It is a frequency modulation synthesizer with 4 oscillators with individually assignable waveforms. It works only inside Ableton Live

Ableton Live

Ableton Live is a loop-based software music sequencer and DAW for Mac OS and Windows by Ableton. The latest major release of Live, Version 8, was released in April 2009. In contrast to many other software sequencers, Live is designed to be an instrument for live performances as well as a tool for...

. Operator is unique in that each oscillator's waveform can be custom crafted through additive synthesis

Additive synthesis

Additive synthesis is a technique of sound synthesis that creates musical timbre by explicitly adding sinusoidal overtones together.The timbre of an instrument is composed of multiple harmonic or inharmonic partials , of different frequencies and amplitudes, that change over time...

 by selecting the level of each individual harmonic

Harmonic

A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency, i.e. if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, . . . etc. The harmonics have the property that they are all periodic at the fundamental...

in the resultant waveform.