What does the term 'crescendo' refer to in music dynamics?

The term 'crescendo' specifically refers to a gradual increase in the volume of music. It indicates that the dynamics of a piece are rising, creating a sense of intensity or build-up as the volume grows louder over a certain duration. This technique is often used by composers to enhance the emotional impact of the music, drawing listeners in and creating anticipation. A crescendo can be notated in sheet music with the symbol "cresc." or a series of lines that indicate the direction of the dynamic change.

While other terms describe different dynamic actions—such as a decrescendo (growing softer), a dynamic marking that remains steady at the same volume, or a sudden change in volume known as a subito—crescendo is distinct for its focus on increasing volume over time. This makes it an essential concept in understanding how dynamics contribute to musical expression and development.