Tempos

In musical terminology, tempo [ˈtɛmpo] ("time" in Italian; plural: tempi [ˈtɛmpi]) is the speed or pace of a given piece or subsection thereof, how fast or slow. Tempo is related to meter and is usually measured by beats per minute, with the beats being a division of the measures, though tempo is often indicated by terms which have acquired standard ranges of beats per minute or assumed by convention without indication. Tempo may be separated from articulation, or articulation may be indicated along with tempo, and tempo contributes to the overall texture. While the ability to hold a steady tempo is a desirable skill, tempo is changeable, and often indicated by a conductor or drummer. While practicing, an electronic or mechanical device, a metronome, may indicate the tempo, as one usually works one's way up to being able to perform at the proper tempo. In other words, it is the speed at which a passage of music is or should be played.

A piece of music's tempo is typically written at the start of the score, and in modern Western music is usually indicated in beats per minute (bpm). This means that a particular note value (for example, a quarter note, or crotchet) is specified as the beat, and that the amount of time between successive beats is a specified fraction of a minute. The greater the number of beats per minute, the smaller the amount of time between successive beats, and thus faster a piece must be played. For example, a tempo of 60 beats per minute signifies one beat per second, while a tempo of 120 beats per minute is twice as rapid, signifying one beat every 0.5 seconds. Mathematical tempo markings of this kind became increasingly popular during the first half of the 19th century, after the metronome had been invented by Johann Nepomuk Maelzel, although early metronomes were somewhat inconsistent. Beethoven was one of the first composers to use the metronome; in the 1810s he published metronomic indications for the eight symphonies he had composed up to that time.

...
Wikipedia