The Minority

There is a musical world out there that everyone knows about, but few frequent. In clubs with sparse, polite audiences, musicians of the highest calibre perform the most complex music. When one of the musicians steps into the spotlight and improvises for a verse or two, the audience applauds when the solo is over, even if the song is still going on.

Dictionary.com defines jazz as: "music originating in New Orleans around the beginning of the 20th century and subsequently developing through various increasingly complex styles, generally marked by intricate, propulsive rhythms, polyphonic ensemble playing, improvisatory, virtuousic solos, melodic freedom, and a harmonic idiom ranging from simple diatonicism through chromaticism to atonality." 

As definitions go, that's a start, but there are a couple of problems: not only is it a weak description of most slow jazz styles, it also could apply equally well to some kinds of rock, latin and even certain modern classical music. So what makes jazz different from those? I guess we know it when we hear it; there are some jazz traditions of substitution chords, and chords with remote bass notes, some instrumental cliches on piano, bass and sax, and some peculiarly 'jazzy' vocal styles. The definition gets even harder to nail down when you add in fusion styles, hyphenating jazz- primarily with rock, but also with latin and other world music elements.

I'm going to admit that I don't reach for jazz albums first when I decide to put on some music, and it's a world that, like most people, I haven't spent much time in. There was l little window, however, back in the mid-seventies when Jeff Beck put out back-to-back albums ("Blow By Blow" and "Wired") of instrumental jazz fusion and won over a huge audience of blue-jeaned rock fans, and I was one of them. (I would never have dreamed at the time that within the next few years I would be playing in a band that was opening for him)

Here's Jeff Beck playing a Mingus piece, a lovely example of the reasons jazz fans love it when it's good; the melody is seductive, the changes are emotional, and the playing is very, very superior. 
(I was amused that one commenter on YT claims that after hearing this song he threw his guitar out the window and never played again)