A crescendo is a gradual increase in loudness. The marking appears in the score as a hairpin opening to the right or as the word itself. Performers respond by adding more air, bow pressure, or mallet force over the indicated span.

Crescendos create direction and excitement. A long crescendo can build tension across an entire phrase or section; a short one can emphasize a single gesture. The opposite marking, diminuendo or decrescendo, produces the reverse effect. Together they give music its dynamic shape.

Controlling a smooth crescendo requires technical control so the sound grows without sudden jumps or loss of tone quality. Ensembles must coordinate the increase carefully so no section overtakes the others. Composers use crescendos to highlight structural arrivals or to intensify emotional expression.

Listening for well-shaped crescendos is one of the pleasures of attentive performance.