What is a standard adopted by manufacture use for interfacing synthesizer equipment?

A standard commonly adopted for interfacing synthesizer equipment is the MIDI (Musical Instrument Digital Interface) protocol. Established in the early 1980s, MIDI allows electronic Musical Instruments, computers, and other related devices to communicate and synchronize with each other. It transmits performance data such as notes, velocity, and control changes, enabling musicians to create complex compositions and control multiple devices seamlessly. Other standards, like CV/Gate (control voltage/gate) systems, are also used, particularly in modular synth setups.