The is an orchestral piece that is played at the beginning of a larger work such as an opera, oratorio, or suite. it serves to set the mood of the larger work and to alert the audience that the piece is about to begin.

I believe it is the Overture, another word for prelude or preliminary. 

The gregorian chant was a major cultural milestone in the middle ages. it was one of the first codified forms of music meant to be played as written, where previously it was difficult to mass-produce and disseminate any music. what's more, these chants were also some of the first examples of musical notation: the notes and bars of today's music sheets are a reflection of centuries of evolution beginning with these chants. it became official throughout the entirety of the catholic church, meaning that nearly all of europe followed this musical notation and styling.

Graphic design is still art, although it differs highly from the traditional forms of art. when someone is creating a piece of art using technology, it still takes time, effort, and creativity to make something look visually appealing. art itself is defined as "the expression or application of human creative skill and imagination." working on computers and using design programs still require the artist to understand lines, shape, form, value, color, space,  and all of the other elements that traditional artists study. they still need to be able to evoke thoughts and emotions through their piece. art does not have to be physically created for it to count as art. so, i think graphic design should still be considered art.