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. Its West African pedigree is evident in its use of blue notes, improvisation, polyrhythms, syncopation, and the swung note.
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)