While the term Neoclassicism typically refers to the Enlightenment trends that focused on ancient Greece and Rome, in music the term refers to twentieth-century music that looked back to the "Classical" music of the eighteenth century. The composers Igor Stravinsky and Alfredo Casella were important figures in this movement.

In musical notation, the note "piano" above a clef indicates that the music should be played softly. Often such a mark, sometimes abbreviated with just a "p," will come in the middle of a piece to indicate a change of volume. The opposite notation is "forte," which indicates that the music should be played loudly.

Philip Glass was part of a group of composers who used simple motifs that were repeated over steady beats. This music was dubbed "minimalism" by crtics, but also embraced by the figures who founded it, as it expressed their desire to reduce music to its essentials.

The eighty-eight notes on a keyboard are produced by pressing white and black keys. The black keys are positioned slightly higher and farther back, as they hold all of the sharp and flat notes on the twelve-tone chromatic scale. This arrangement allows the natural notes to be played more easily, and make the non-natural notes more obvious.

Accordions have been used in a wide variety of traditional folk music around the world. Accordions, free reed instruments that can be played with either a keyboard or diatonic buttons, provide a multitonal and varied sound that can accompany a voice all on its own. One notable exception to the kind of folk music that features the accordion is bluegrass, a folk style developed in Appalachia that exclusively features string instruments such as the guitar, banjo, fiddle, dobro, and mandolin.

In the early twentieth century, many composers sought to go beyond the traditional eight note scale of Western music. The first composer to set out a system to use atonality in compositions was Arnold Schoenberg, who created a "twelve tone system" in the 1920s of chromatic tones that gave each note equal weight. The system was used heavily by composers after World War II.

The time signature is two numbers, which are stacked one on top of the other and are placed at the beginning of a piece of music. The top number indicates how many beats are in each measure. The bottom number indicates how long each beat will last, with a four meaning a quarter more, and an eight an eighth note.

The clarinet is a woodwind instrument, and produces sound like all woodwind instruments, by the player blowing through a reed and controlling the sound by opening and closing valves with his or her fingers. Every other instrument listed in some way uses a keyboard, or in the case of the organ, multiple keyboards.

Bluegrass is a form of folk music developed in the middle of the twentieth century, primarily in Appalachia. The musical form developed around string instruments, which were available and primarily used in square and barn dances in the region. The clarinet, a wind instrument, is the only instrument listed that is not a key element of bluegrass ensembles.

Jazz was born in nightclubs in cities throughout the south in the early twentieth century. A common problem for early jazz groups was an inability to be heard, and many advancements in amplifying sound were made because of jazz. As such, quieter acoustic string instruments like the mandolin never made a dent in jazz.