What is Jazz?
Jazz is a label that encompasses many aspects of an internationally loved art form and the culture that surrounds it. Its rich history ties it originally to the songs and rhythms of ancient African societies, which are associated with sacred traditions that in turn made way, if one looks closely enough, for the innovations of modern computing. As European colonials brought slaves to the Americas, the music of Africa came with them, leading to contributions like gospel, ragtime, and, perhaps most importantly, the blues. Jazz music can be "legit:" official and classically regimented, like the Gershwin brothers and Scott Joplin; it can also be "free:" chaotic, improvised, and experimental, like Ornette Coleman and the later work of Miles Davis. Jazz is also found in dance, art, and poetry, and no form of rock or hip-hop would have ever happened without it.
Jazz music has its earliest roots in Africa. Throughout the 1700s Africans were taken by the millions to the North American colonies for the purpose of slavery. There, on plantations, slaves would sing work songs with each other in a call and response manner. These songs still exist in the form of Spirituals today.
With the ending of the Civil War in 1865 came freedoms these men and women, most of whom had been born in America, had never known before. Also around this time, a new music started popping up around the Louisiana delta, in and around New Orleans. Marching bands were formed, with odd instrumentations consisting mostly of brass instruments, playing music almost entirely by ear.
In the early 1900s, a new style of music called Ragtime started gaining popularity. Ragtime is characterized by the stride left-hand part ("boom chick" type of bass line) and syncopated rhythms in the right hand part on the piano. Famous names of this genre include Scott Joplin and "Jelly Roll" Morton.
Also out of New Orleans, along with Ragtime, was the Dixieland Jazz style, characterized by the distinct style of counterpoint and stride bass line.
Then, just a couple decades later, came a new style called Swing. The man most responsible for the growth of Swing in the mainstream was Louis Armstrong. Armstrong was known for playing using the "swing eighths", which is characterized by playing the two eighth notes of a subdivided quarter in a non-symmetrical fashion. Below is an example of how straight eighths (normal eighths) music might be notated:
In the swing style, however, 8th notes are often played as though one subdivides the quarter note as an eighth note triplet and plays a quarter note-eighth note combination. This is a rather technical way to describe it, and indeed people originally thought that it was music solely of feeling that could not be written down. The first person to write down jazz successfully was Jelly Roll Morton. Swing rhythm might be notated as below:
Sometimes, swing rhythms are played as a dotted quaver followed by a semiquaver. This is sometimes called heavy swing, and is most common in the Dixie Land style. This would be notated:
Playing music with a swing is characteristic of nearly all forms of jazz, and should not be confused with the Swing music sub-genre.
In the 1940s, after the Great Depression and two World Wars, a new style of music was emerging out of New York city. Bebop sprouted out of the artists' need for self-expression, unconstrained by the demands of the dancing public, for whom Swing music evolved. Additionally, during the second world war, the overall movement and unavailability of men of a fighting age (who made up the majority of jazz musicians) meant that the traditional "big band" format became untenable, due to a lack of musicians, which led to a greater emergence of smaller groups which were more suited to the less constrained style of bebop.
Bebop is characterized by fast tempos and improvisation based on harmonic structure rather than melody.
Jazz quickly evolved throughout the 20th Century. A sub-genre was Swing, which featured high energy and infectious melodies. Benny Goodman and Glenn Miller are notable leaders.
After Swing, Cool Jazz became popular, growing from its West Coast roots. One of the most popular musicians of the genre is Dave Brubeck, who with his album Time Out first challenged the notion that jazz could only be in 4/4 or waltz-style 3/4 time. It ignited a firestorm of controversy, but was immensely popular thanks to the single "Take Five."
An era of experimentation followed Cool Jazz with Miles Davis leading the way. Fusion, the attempt to blend jazz and rock and roll, also came about during this time. Notable fusion artists include Jaco Pastorius and the band Weather Report. Latin jazz also exploded during this time, led by people such as Chick Corea. Free Jazz also developed during this era, lead by Ornette Coleman. Free Jazz is played without a definite rhythmic structure and while there is some element of randomness, there is still a cohesive bond between the players. Some dispute whether Free Jazz is real jazz, or even real music.
Recently, jazz has splintered into a large grouping of subgenres without one truly leading the way. Smooth jazz has gained some popularity thanks to artists like Kenny G, but it is reviled by many as "not really jazz" because no improv happens and usually 'smooth' songs are just vamped on one chord. Other artists are trying to blend jazz with other forms of music, such as the band Béla Fleck and the Flecktones who combine jazz with bluegrass, funk, latin, reggae, and Asian music. Fleck himself plays banjo, an indication of the iconoclastic nature of the group.
(this should get you all off to a nice start)