Final answer:
Beethoven's main compositions were symphonies, sonatas, and string quartets. He was known for his significant contributions to these forms and for his role in transitioning music from the Classical to the Romantic era.
Step-by-step explanation:
Ludwig van Beethoven composed symphonies, sonatas, and string quartets:
Ludwig van Beethoven was a pivotal figure in classical music, bridging the Classical and Romantic eras. His compositions include a wide range of genres but are primarily associated with symphonies, piano sonatas, and string quartets. These forms were evident in Classical period music, as established by composers like Haydn and Mozart, and Beethoven's work did indeed start within that classical framework.
Over time, his music incorporated more of the Romantic elements of expression and emotional depth. Beethoven's symphonies, such as his renowned Ninth Symphony, expanded the orchestra and integrated new levels of emotional expressiveness, which became hallmarks of the Romantic era. His sonatas, such as the "Moonlight Sonata," pushed the boundaries of piano music with their technical demands and expressive range.