Contemporary classical music can be understood as belonging to the period that started in the mid-1970s to early 1990s, which includes modernist, postmodern, neoromantic, and pluralist music. However, the term may also be employed in a broader sense to refer to all post-1945 musical forms.
Generally "contemporary classical music" includes modern forms of art music such as post-tonal music after the death of Anton Webern, including serial music, electroacoustic music, musique concrète, experimental music, atonal music, minimalist music, etc; and post-1975 music such as Spectral music, post-minimalism, sound art, etc. Notable composers include Philip Glass, John Adams, Steve Reich, Thomas Adès, Olivier Messiaen, Pierre Boulez, Arvo Pärt, Terry Riley and Charles Ives. Continue reading from ClassicFM
Unlike the symphony and sonata forms of the past, there was a breakaway towards aleatoric music (sometimes known as chance music), which provided greater flexibility over the outcome of a work. As opposed to clear notations that would direct an interpretation, a composer might choose to give the performer a wide range of interpretative options or instead leave the composition to indeterminate factors.
One champion of aleatoric music was John Cage. His most famous piece, 4’33, has minimal directions and no “music” at all. The absence of sound from the performer was meant to draw attention to the audience; in essence, the main argument of Cage’s work is that the audience also contributes their sounds to the event of a live performance. Other composers during this time began to experiment with this indeterminacy of composition. Another American composer, Lamonte Young, was inspired heavily by John Cage and produced a set of pieces with various performance instructions entitled Compositions 1960. Continue reading from CMuse
Contemporary Timeline (Oxford Music Online)
A Grand Tour of Contemporary Music (Slate)
A Beginner's Guide to Modern Classical Music (Luke Muehlhauser)
10 Contemporary Black Composers You Should Know (ArtsBoston)
Understanding the Differences Among Contemporary Classical Music Genres (Connolly Music)
10 Contemporary Women Composers You Should Know (AllClassical)
The Sounds of Music in the Twenty-First Century (The New Yorker)