A MIDI interface is a device that connects musical instruments, computers, and other equipment using the MIDI (Musical Instrument Digital Interface) protocol. It allows different devices to communicate and control each other, enabling musicians to create and manipulate music digitally. MIDI interfaces can be found in various forms, including USB devices and traditional 5-pin connectors. These interfaces are essential for music production, as they facilitate the transfer of musical data, such as notes and control signals, between devices. By using a MIDI interface, musicians can connect keyboards, synthesizers, and computers, enhancing their creative possibilities in music composition and performance.