Avant-garde music is music that is considered to be at the forefront of experimentation or innovation in its field, with the term " avant-garde " implying a critique of existing aesthetic conventions, rejection of the status quo in favor of unique or original elements, and the idea of deliberately challenging or alienating audiences. 
Avant-garde music may be distinguished from experimental music by the way it adopts an extreme position within a certain tradition, whereas "experimental music" lies outside tradition. In a historical sense, some musicologists use the term "avant-garde music" for the radical compositions that succeeded the death of Anton Webern in 1945. Don Michael Randel writes that this period began with the work of Richard Wagner, whereas Edward Lowinsky cites Josquin des Prez. The term may also be used to refer to any other post-1945 tendency of modernist music not definable as experimental music, though sometimes including a type of experimental music characterized by the rejection of tonality.
Classical and contemporary music
Although some modernist music is also avant-garde, a distinction can be made between the two categories. According to scholar Larry Sitsky, because the purpose of avant-garde music is necessarily political, social, and cultural critique, so that it challenges social and artistic values by provoking or goading audiences, composers such as Igor Stravinsky, Richard Strauss, Arnold Schoenberg, Anton Webern, George Antheil and Claude Debussy may reasonably be considered to have been avant-gardists in their early works (which were understood as provocative, whether or not the composers intended them that way), but the label is not really appropriate for their later music. For example, modernists of the post–World War II period, such as Elliott Carter, Milton Babbitt, György Ligeti, Witold Lutosławski, and Luciano Berio, never conceived their music for the purpose of goading an audience, and so cannot be classified as avant-garde. Composers such as John Cage and Harry Partch, on the contrary, remained avant-gardists throughout their creative careers.
The 1960s saw a wave of avant-garde experimentation in popular jazz, represented by artists such as Ornette Coleman, Sun Ra, Albert Ayler, Archie Shepp, John Coltrane and Miles Davis.   In the rock music of the 1970s, the "art" descriptor was generally understood to mean "aggressively avant-garde" or "pretentiously progressive".  Post-punk artists from the late 1970s rejected traditional rock sensibilities in favor of an avant-garde aesthetic.  In 1988 the writer Greg Tate described hip-hop music as "the only avant-garde around, still delivering the shock of the new."