Musical Modernism can be seen as the moment when music emerges with its freedom from the style of the Romantic era -started from the end of the nineteenth century to the end of the Second World War - and acquires new ideas and freedom. With the political unrest and chaos that took over European countries, -which drew the countries into World War I- composers and artists began to find and create new ways to express themselves. They enthusiastically began to discover the art of oriental countries with the hope of finding new ways of expression. Key changes, irregular rhythms, tone clusters, anguished and antagonistic melodies, expressionistic, abstract and unusual ideas prevail over the music, traditional structures recreated or composed with unusual techniques, and the music acquires non-Western elements. Thus the music of the 20th century shows its rebellion against the Romantic era – and any other era really – and earns the name "modern era" and a new importance through this movement in history. Furthermore, with the modernist movement, music gained interest as a subject that it had never had before. reproduction of Nature but with the mysterious corresponding meanings on life itself. With the modernist movement, emotions other than love, anger, and joy began to be depicted more confidently and concisely. Composers like Claude Debussy, Igor Stravinsky and Arnold Schönberg are very... center of paper... they were his guard against harmonic resolution in his music. He was fascinated above all by the rhythm of the waltz and the march - as he used these rhythms in most of his works - however with the title "Schoenberg" he brought the same complex and irregular approach to these rhythms too. The irregular tempos showing differences even from one bar to another in the same piece and the rhythms and time signatures he used in his compositions were constantly changing. To conclude, these three revolutionary composers that I have analyzed in this essay have brought so many levels and layers to 'Modern Music'. With their contribution the modern era broke away from romanticism. Without Debussy's unique and entertaining compositions, Stravinsky's rhythmic and dynamic layers and new ideas, Schönberg's creative theories and the revolutionary 12-tone system one cannot think of a modern era..