During the 20th century, many musicians tried to create new types of music that went against the traditional norms of previous musical periods. This is because the 20th century was defined by a search for innovation and a desire to explore alternatives to the past. This was a dominant tendency in all art.
One of the innovations of musicians at this time was the exploration of alternatives to the traditional tonal system. For example, in some cases, the central tone was maintained while other elements were discarded. In others cases, composers borrowed ideas from music that came from outside western Europe. Polytonality (the use of two or more keys at a time) was a new approach to pitch organization. The 1920s saw the development of the twelve-tone-system. These changes made the new music of the 20th century unusual and innovative.
