Tempo is the pulse of music. Without it, notes remain marks on paper; with it they come alive and become experience.
Historically, tempo was indicated with Italian terms (Adagio, Allegro, Presto), but with the invention of Mälzel's metronome (1815) a precise numerical scale — BPM — appeared. Today composers use both: emotional description plus an exact number.
Tempo affects not only speed but the very character and meaning of music: the same theme, played slowly or fast, may sound like a lament or a dance. That is why 20th-century composers increasingly give an exact BPM figure alongside the Italian term. Separate markings (accelerando, ritardando, rubato) govern the flexible change of tempo, making it a living, “breathing” expressive device.
