Acronym for “User Interface.” All electric or electronic items have a user interface. On a toaster, for example, the user interface allows you to set the length of time bread will toast, from light to burnt crisp. The same is true for stoves, automobiles, DVD players and so forth. For our application, which is music technology, the user interface may consist of knobs, switches, displays, sliders or buttons used to make various settings (i.e. adjusting volume). For electronic gear, the user interface may consist of just a few controls (as on a stompbox) to a dizzying array (think of those early modular synthesizers).