What does "tempo" refer to in music?

In music, "tempo" specifically refers to the speed at which a piece is performed. It is measured in beats per minute (BPM) and indicates how fast or slow the music should be played. Tempo can significantly influence the feel and character of a piece; for example, a fast tempo might create excitement or urgency, while a slow tempo could evoke calmness or sadness. Understanding tempo is crucial for musicians as it guides their interpretation and performance of the music.

The other options touch on different musical concepts: loudness pertains to dynamics, mood relates to the emotional setting or atmosphere created by the music, and the order of notes refers to melody and harmony rather than tempo. Each of these elements contributes to the overall performance but does not specifically define the term "tempo."