What is meant by development in music?

Development in music refers to the modification of themes and motifs. This process often involves altering a given theme through various techniques such as changing its rhythm, harmony, or melody. In classical music, the development section of a sonata form is where the composer explores and transforms the initial themes, creating variations that maintain the core identity while introducing new elements. This contrasts with simply repeating a melody or merely playing it louder, which do not involve the kind of creative exploration that development entails. Additionally, the creation of entirely new themes would fall under a different compositional process rather than development of existing material, which focuses on transformation and variation.