The metronome is an instrument used to measure time and indicate the beat of musical compositions. The metronome produces a regular, metric tick (beats, clicks), which can be set in beats per minute. These beats represent a marked aural pulse; some metronomes also include a visual synchronized movement, for example a swinging pendulum.

The origins of the metronome date back to the early 19th century, when it was patented by Johann Maelzel in 1815 as a tool for musicians, entitled «Instrument or Machine for the Improvement of Musical Performance, called Metronome». This instrument is used by musicians to help maintain a constant time while playing, in the same way to correct problems of time of the musician, or to help internalize the sense of time and rhythm in music learners. After being patented in 1815, it is believed that the first notable composer to use the metronome in his music was none other than Ludwig Van Beethoven himself.

Because not all people have the same notion of rhythm and time, some experts suggest that the use of the metronome goes against the essence of music, since it has been shown that the Metronome Time is very different from Musical Time, so in a musical piece with different emotional elements, in which many rhythms can be given, the use of the metronome is not appropriate. Musical time is almost always measured in beats per minute (BPM); therefore the metronomes can be set to different times, which usually vary from 40 to 208 BPM; another denotation for metronome beat is MM (or MM), Mälzel Metronome.

This denotation is usually followed by a numerical value indicating the time, for example “MM = 60”. There are currently three types of metronomes: mechanical, electrical and software. Due to its infallible precision in maintaining a certain time, the metronome has also been used as a musical instrument; such is the case of the 1962 composition by György Ligeti «Poème Symphonique for 100 Metronomes». Similarly, Maurice Ravel used three metronomes at different speeds for the intro to his opera “L’heure Espagnole”.