Genre Motif/Jazz

Jazz is a very broad category that encompasses a ton of styles, but most people only recognize the type that emphasizes brass and piano. Generally gets used to convey the the first half of the 20th century or otherwise make a character/setting seem old fashioned without the elitist stigma of classical music.

Examples:
 * In The Talented Mr. Ripley, all the characters besides the title one listen to jazz (which, for its time, was the music of free-spirited people before Rock came along).
 * According to the Spongebob SquarePants episode "Grandma's Kisses", one of the requirements of being a grown-up is developing "a taste for free-form jazz."
 * Temperance Brennan in the TV series Bones enjoys jazz, much to the surprise of Booth.
 * The entire soul and fiber of Cowboy Bebop is based on 70's jazz.
 * Christopher Lewis in Seducing Dr. Lewis loves fusion jazz, much to the chagrin of Steve and GÃ©rmain, as a way to portray him as a trendy, sophisticated yuppie.
 * In Sonic Adventure 2, Rouge's theme and the background music to all of her levels is jazz-based.
 * Baccano! uses this as its core much in the same way that Cowboy Bebop does, though with a focus on various forms of 20's/30's jazz.
 * Woody Allen frequently uses jazz for the soundtracks to his movies.
 * Capcom's Alph Lyla sound team, from about 1997 to 2000, had an obsession with filling games entirely with Jazz fusion soundtracks. See Breath of Fire III and Marvel vs. Capcom 2.
 * One of the motifs in Haruki Murakami's After the Quake is Jazz music as a metaphor in freedom in life.