What are Beethoven's sketchbooks?

Beethoven's sketchbooks are a collection of notebooks in which the composer jotted down musical ideas, drafts, and revisions throughout his career. These sketchbooks provide insight into his creative process, showing how he developed themes and structured his compositions. They include sketches for many of his major works, revealing Beethoven's meticulous approach to music and his innovative techniques. Scholars study these notebooks to gain a deeper understanding of his artistic evolution and compositional methods.