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.

From its beginnings in the early 20th century jazz has spawned a variety of subgenres: New Orleans Dixieland dating from the early 1910s, big band-style swing from the 1930s and 1940s, bebop from the mid-1940s, a variety of Latin jazz fusions such as Afro-Cuban and Brazilian jazz, free jazz from the 1950s and 1960s, jazz fusion from the 1970s, acid jazz from the 1980s (which added funk and hip-hop influences), and Nujazz in the 1990s. As the music has spread around the world it has drawn on local, national, and regional musical cultures, its aesthetics being adapted to its varied environments and giving rise to many distinctive styles.

The origin of the word jazz is one of the most sought-after word origins in modern American English. The word's intrinsic interestthe American Dialect Society named it the Word of the Twentieth Centuryhas resulted in considerable research, and its history is well documented. The word began as West Coast slang around 1912, the meaning of which varied but did not refer to music or sex. It came to refer to the music in Chicago around 1915. The music was played in New Orleans prior to that time but was not referred to by that name. The word jazz makes one of its earliest appearances in San Francisco baseball writing in 1913. Jazz was introduced to San Francisco in 1913 by William (Spike) Slattery, sports editor of the Call, and propagated by a band-leader named Art Hickman. It reached Chicago by 1915 but was not heard of in New York until a year later. One of the first known uses of the word appears in a March 3, 1913, baseball article in the San Francisco Bulletin by E. T. "Scoop" Gleeson.