Arnold Schoenberg (1874-1951) was an Austrian-American composer, music theorist, and painter, widely regarded as a pivotal figure in the development of 20th-century music. He is best known for his role in the creation of atonal music and the twelve-tone technique, which revolutionized compositional practices. Schoenberg's notable works include "Verklärte Nacht" (Transfigured Night), a string sextet that exemplifies late-Romantic lushness, and "Pierrot Lunaire," a melodrama for voice and chamber ensemble that employs atonality and Sprechstimme. His twelve-tone method, first articulated in "Composition with Twelve Tones" (1923), organized pitches into a fixed series, fundamentally altering the approach to melody and harmony. Schoenberg's impact on music extends beyond his compositions; he influenced generations of composers, including Alban Berg and Anton Webern, forming the core of the Second Viennese School. His theories and practices laid the groundwork for numerous avant-garde movements, challenging traditional notions of tonality and expanding the possibilities of musical expression. Schoenberg's legacy continues to resonate in contemporary classical music and beyond, marking him as a seminal figure in modern music history.