What does "tempo" refer to in music?

"Tempo" refers specifically to the speed at which music is performed, indicating how fast or slow a musical piece is meant to be played. It is a crucial aspect of musical expression that affects the overall feel and character of a piece. Composers often express tempo through specific terms, such as "allegro" for a fast pace or "adagio" for a slower one, and sometimes also with metronome markings indicating beats per minute.

In contrast, the other concepts do not pertain to speed. Harmony relates to the vertical aspect of music involving chords and their progression, while melody refers to the horizontal aspect, focusing on the main tune or theme of the music. The key signature, on the other hand, denotes the tonal center of the piece and identifies which sharps or flats are used but is unrelated to the speed of performance. Understanding that tempo is focused solely on pace helps musicians interpret and convey the intended emotion and dynamics of a piece.