Igor Fyodorovich Stravinsky was a Russian composer, pianist, and conductor. He is widely considered one of the most important and influential composers of the 20th century.
Stravinsky's compositional career was notable for its stylistic diversity. He first achieved international fame with three ballets commissioned by the impresario Sergei Diaghilev and first performed in Paris by Diaghilev's Ballets Russes: The Firebird (1910), Petrushka (1911) and The Rite of Spring (1913). The last of these transformed the way in which subsequent composers thought about rhythmic structure and was largely responsible for Stravinsky's enduring reputation as a musical revolutionary who pushed the boundaries of musical design. His "Russian phase" which continued with works such as Renard, The Soldier's Tale and Les Noces, was followed in the 1920s by a period in which he turned to neoclassical music. The works from this period tended to make use of traditional musical forms (concerto grosso, fugue and symphony), drawing on earlier styles, especially from the 18th century. This style was often referred to as Neoclassicism. In the 1950s, Stravinsky adopted serial procedures. His compositions of this period shared traits with examples of his earlier output: rhythmic energy, the construction of extended melodic ideas out of a few two- or three-note cells and clarity of form, and of instrumentation.

Leonard Bernstein was one of the most iconic American composers and conductors of the 20th century, and was among the first American musicians who gained worldwide recognition.
He actually made his breakthrough as a conductor by chance, when he suddenly had to stand in for the ailing Bruno Walter for a concert by the New York Philharmonic in 1943. The concert, which was broadcast live on radio, received critical acclaim from the press. Bernstein would soon become a sought-after guest conductor.
From 1958 till 1969, Bernstein was principal conductor of the New York Philharmonic, with which he performed amongst others the complete symphonies of Mahler, which sparked a renewed interest in the music of the Austrian composer in the United States. He was also an advocate of the music of American composers, in particular that of his close friend Aaron Copland. Bernstein recorded nearly all of his orchestral works, and paid much attention to his music in his popular television series Young People’s Concerts, in which he introduced a young audience to classical music.
As a composer, Bernstein is primarily known for his accessible theatre works such as Wonderful Town, Candide and The West Side Story, which still is his most popular work. He also composed three symphonies and several shorter chamber works. In his music he fused elements of Jewish music, theatre music and jazz with those of composers like Copland, Stravinsky and Gershwin.

Arnold Schoenberg was one of the most influential composers of the 20th century, but perhaps also one of the least listened to. Strikingly, Schoenberg was self-educated, even though his music is imbedded in complex music theory. It was Schoenberg who definitely departed from tonality and he developed the twelve tone technique. In this composition style, one has to use every twelve tones of the scale, before one can be repeated. The struggle to adhere to this dogma is clearly audible: his music is tense, hectic and particularly acute - and therefore at times not that accesible to occasional listeners.

Nevertheless, his music and his liberation of tonality had an enormous impact on all composers that came after him. Together with the music of his students Alban Berg and Anton Webern, his style is often referred to as the Second Viennese School, parallel to the First Viennese School of Mozart, Haydn and Beethoven, who, in a similar vein, changed the history of music for good.

His most performed works are his string sextet Verklärte Nacht, his five Orchestra pieces op. 16, and his opera Moses und Aron. The development of Schoenberg's music can be heard in his Five String Quartets in particular.