Which entity is this text about?

Kurt Julian Weill (March 2, 1900 - April 3, 1950) was a German composer, active from the 1920s in his native country, and in his later years in the United States. He was a leading composer for the stage who was best known for his fruitful collaborations with Bertolt Brecht. With Brecht, he developed productions such as his best-known work The Threepenny Opera, which included the ballad "Mack the Knife". Weill held the ideal of writing music that served a socially useful purpose.

Back in Berlin, Weill had an interview with Ferruccio Busoni in December 1920. After examining some of Weill's compositions, Busoni accepted him as one of five master students in composition at the Preussische Akademie der Kunste in Berlin.  From January 1921 to December 1923, Weill studied music composition with him and also counterpoint with Philipp Jarnach in Berlin. During his first year he composed his first symphony, Sinfonie in einem Satz, as well as the lieder Die Bekehrte (Goethe) and two Rilkelieder for voice and piano. To support his family in Leipzig, he also worked as a pianist in a Bierkeller tavern. In 1922, Weill joined the November Group's music faction. That year he composed a psalm, a divertimento for orchestra, and Sinfonia Sacra: Fantasia, Passacaglia, and Hymnus for Orchestra. On November 18, 1922, his children's pantomime Die Zaubernacht (The Magic Night) premiered at the Theater am Kurfurstendamm; it was the first public performance of any of Weill's works in the field of musical theatre.  Out of financial need, Weill taught music theory and composition to private students from 1923 to 1925. Among his students were Claudio Arrau, Maurice Abravanel, Heinz Jolles (later known as Henry Jolles), and Nikos Skalkottas. Arrau, Abravenel, and Jolles remained members of Weill's circle of friends thereafter, and Jolles's sole surviving composition predating the rise of the Nazi regime in 1933 is a fragment of a work for four pianos he and Weill wrote jointly.  Weill's compositions during his last year of studies included Quodlibet, an orchestral suite version of Die Zaubernacht, Frauentanz, seven medieval poems for soprano, flute, viola, clarinet, French horn, and bassoon, and Recordare for choir and children's choir to words from the Book of Lamentations. Further premieres that year included a performance of his Divertimento for Orchestra by the Berlin Philharmonic under the direction of Heinz Unger on April 10, 1923, and the Hindemith-Amar Quartet's rendering of Weill's String Quartet, Op. 8, on June 24, 1923. In December 1923, Weill finished his studies with Busoni.
Kurt Weill