A synthesizer is an electronic instrument, capable of producing a wide variety of sounds by generating and combining signals of different frequencies. A keyboard typically operates it. There are three main types of synthesizers that differ in operation; these include analog, digital and computer software-based. Synthesizers create electrical signals, rather than direct sounds, which are then processed through a loudspeaker or headphones.

Synthesizers are most commonly equipped with a piano-style keyboard. Each key of the keyboard acts as a switch, which can be used to turn electronic circuits on and off. Although synthesizers are the most common input devices other devices such as a mouthpiece, strings, guitars, drum pads or a computer can be used to control a synthesizer. Unlike other instruments, the synthesizer is capable of generating a wide range of sounds, either to imitate other instruments, or to create new sounds. Many well-known music artists commonly use the synthesizer worldwide.

A digital synthesizer
A digital synthesizer is a synthesizer that uses digital signal processing (DSP) techniques to make musical sounds. Electronic keyboards make music through sound waves. The very earliest digital synthesis experiments were made with general-purpose computers, as part of academic research into sound generation.

Early commercial digital synthesizers used simple hard-wired digital circuitry to implement techniques such as additive synthesis and FM synthesis, becoming commercially available in the early 1980s.

Other techniques, such as Wavetable synthesis and physical modeling, only became possible with the advent of high-speed microprocessor and digital signal processing technology. One of the earliest commercial digital synthesizers was the Synclavier.

Some digital synthesizers now exist in the form of “softsynth” software that synthesizes sound using conventional PC hardware, though they require careful programming and a fast CPU to get the same latency response as their dedicated equivalents. In order to reduce latency, some professional sound card manufacturers have developed specialized digital signal processing hardware. Dedicated digital synthesizers frequently have the advantage of onboard accessibility, with switchable front panel controls to peruse their functions, whereas software synthesizers trump their dedicated counterparts with their additional functionality, against the handicap of a mouse-driven control system.

Digital synthesizers are generally more flexible than analog synthesizers, though aficionados claim that an analog synthesizer develops a personal sonic character as it ages.