A polyphonic synthesizer is an electronic musical instrument that can produce multiple notes simultaneously. Unlike monophonic synthesizers, which can only play one note at a time, polyphonic synthesizers allow musicians to create chords and complex harmonies. They use various sound generation methods, such as subtractive synthesis, additive synthesis, or wavetable synthesis, to create a wide range of sounds. These synthesizers often feature a keyboard interface, enabling players to easily access different pitches. Many polyphonic synthesizers also include built-in effects and modulation options, enhancing their sound design capabilities. Popular examples include the Yamaha DX7 and the Roland Juno-106.