What important twentieth-century theoretical model did Arnold schoenberg develop?

Arnold Schoenberg developed the twelve-tone technique, an important theoretical model in the twentieth century. This method involves using a series of all twelve notes of the chromatic scale in a specific order, called a "tone row," which serves as the basis for a composition. The twelve-tone technique revolutionized the approach to melody and harmony, allowing for atonality and greater freedom in musical expression. Schoenberg's work laid the groundwork for many modern composers and significantly influenced contemporary music.