Jazz is a musical tradition and style of music that originated at the beginning of the 20th century in African American communities in the Southern United States from a confluence of African and European music traditions. From its early development until the present, jazz has incorporated music from 19th and 20th century American popular music.[1] Its West African pedigree is evident in its use of blue notes, improvisation, polyrhythms, syncopation, and the swung note.[2]
The word "jazz" (in early years also spelled "jass") began as a West Coast slang term and was first used to refer to music in Chicago in about 1915.

(extract from Wikipedia 2011)