metronome is any device that produces regular, metrical ticks (beats). These ticks represent a fixed, regular aural pulse; some metronomes also include synchronized visual motion (e.g. pendulum-swing). The metronome dates back to the early 19th century. Though the metronome was conceived as a tool for music, some musicians consider it to be a highly controversial tool inthis respect: there are musicians who reject the metronome altogether.
A metronome is used by some musicians for practice in maintaining a consistent tempo, or rubato composers around a fixed beat - yet other musicians view this method of practice negatively. A metronome can be used by composers, as an approximate way of specifying the tempo- yet some composers and musicians consider these metronome-tempo-marks to have only little value, or to hinder creative musical interpretation: Brahms has remarked: "I am of the opinion that metronome marks go for nothing. As far as I know, all composers have, as I, retracted their metronome marks in later years."