What does a fermata instruct a musician to do?

A fermata is a musical symbol that indicates to the musician that they should hold a note or rest longer than its written value. This pause can create a dramatic effect or allow for a moment of emphasis in the music. It's a signal for interpretation and expression, giving the performer the freedom to extend the duration of a pitch or silence, which enhances the emotional impact of the music.

The other options do not accurately represent the function of a fermata. For instance, playing louder or changing the tempo are separate expressions in musical dynamics and tempo markings. Starting a passage again is more about repetition or a da capo instruction and does not relate to the fermata's directive to hold a note or rest. Understanding the purpose of a fermata helps musicians communicate the intended emotional character of a piece effectively.