Why is Franz Schubert especially known for lieder and chamber music?

Franz Schubert is celebrated for his contributions to lieder and chamber music primarily due to his exceptional command of melody and harmony, which allowed him to bridge the Classical and Romantic periods.12

His reputation in these genres is built on several key characteristics:

• Lieder: Schubert composed more than 600 songs, which are noted for their emotional refinement and intimacy. He elevated the genre by treating poetry and music as equally important, often utilizing a virtuoso piano accompaniment to enhance the expressive depth of the lyrics.3
• Chamber Music: In his approximately 28 chamber works, Schubert moved beyond traditional Classical structures. He is recognized for his "unceasing melodic flow" and a "rare harmonic imagination," often repeating melodic sections with innovative, wide-ranging harmonic shifts. Furthermore, his work displays a keen sense of drama, as seen in pieces like the String Quartet No. 14 in D Minor (Death and the Maiden) and his final String Quintet in C Major, which is considered one of his most perfect compositions.4