There are many hypotheses that try to explain this paradox, but the most popular and the most probable hypothesis says that word 'jazz' comes from american slang word 'jasm' which means energy, vigor and... Men's sperm
According to an encyclopedia the term jazz determines a kind of improvised music that was created at the end of the 19th century in New Orleans (south of the united states).
Sources of jazz music originate from popular songs and dances of european music, african rhythms - negro spirituals (songs of Negro slaves of religious nature)
First classical jazz bands were created in the South of USA, big cities like New Orleans, St. Louis, Memphis, Baltimore, in their black districts. They primarily consisted of: -clarinet -cornet -trombone -drums -piano -contrabass
Classical period of jazz music began in 1917 after recording the first jazz panel in NY by Original Dixieland Jazz Band. During this period, instrumental forms and new jazz genres were established.
And two new centers of this music were created: Chicago and NY. The main representatives of this period include King Oliver, Louis Armstrong, Jelly Roll Morton, Creole Jazz Band and New Orleans Rhythms Kings.
The period of swing starts something about 1935 and ends in 1945 and in this style orchestra jazz is strongly dominating. Swing Big Bands were formed by Duke Ellington, Benny Goodman, who became a pattern for all contemporary dance music artists.
Modern jazz begun with the Bebop style after 1945 (Charlie Parker, Dizzy Gillespie), and also in a later jazz Tool (Miles Davis, Stan Getz, Modern Jazz Quartet).
However, initiated in the 1960s by Ornette Coleman Free Jazz (free, going beyond the total system in the sphere of harmony) co-existed with the jazz-rock direction (fusion), which developed until the 1980s.