Arnold Schoenberg or Schönberg was an Austrian-born composer, music theorist, teacher, writer, and painter. He is widely considered one of the most influential composers of the 20th century. He was associated with the expressionist movement in German poetry and art, and leader of the Second Viennese School. As a Jewish composer, Schoenberg was targeted by the Nazi Party, which labeled his works as degenerate music and forbade them from being published. He emigrated to the United States in 1933, becoming an American citizen in 1941.
Schoenberg's approach, bοth in terms of harmony and development, has shaped much of 20th-century musical thought. Many European and American composers from at least three generations have consciously extended his thinking, whereas others have passionately reacted against it.
Schoenberg was known early in his career for simultaneously extending the traditionally opposed German Romantic styles of Brahms and Wagner. Later, his name would come to personify innovations in atonality that would become the most polemical feature of 20th-century classical music.