Composers incorporated all styles of music, such as classical patterns, jazz lines, and romantic melodies. They also created new musical idioms, including Schoenberg's 12-tone system and John Cage's use of nuts, screws, and other objects to alter the sounds of piano strings. Today most people dance to pop tunes and hip-hop, but classical music still abounds. People go to classical concerts to be immersed in interesting new worlds created by the harmonies of a symphony. Movies use classical music to create atmospheres of suspense or peacefulness.
Popular musicians study classical music to learn technique.
Check out the classic reference text, A History of Western Music , by Donald Grout and Claude Palisca.