There are multiple differences that set jazz apart from classical music, including the choice of instruments, the style of music, and how the music is played. Even though the two genres share some of the same instruments, the way the instruments are played and presented reveals the distinct nature of the two forms of music.
One basic element that sets jazz apart from classical music is improvisation. This element is a creative process that enables the jazz musician to be spontaneous by making up music while it is being performed. Classical musicians usually perform musical notes exactly as written out on the page by a composer although in past times major figures such as Mozart and Beethoven were known for their improvisational abilities.
The way that rhythms are performed is another basic element that separates the two styles of music. Even though both genres are based on a regular beat, the beats that are emphasized are different. Whereas classical music generally emphasizes the first beat of each measure, jazz music emphasizes the second beat of each measure and handles rhythm more flexibly, creating what is known as a "swing" effect. This tension created among the beats in jazz is called syncopation, a trait that can be traced back to one of the major precursors of jazz, ragtime. Ragtime itself, though, is sometimes categorized as a form of classical music since it it usually performed as written by composers such as Scott Joplin. Extremely complex rhythmic effects in classical music have been achieved by innovators such as Stravinsky and Messiaen.
Jazz music often features a combination of brass, woodwind, and percussion instruments. Jazz big bands rely heavily on brass instruments, particularly saxophones, which are rarely used by classical composers, and the upright bass in jazz is usually plucked rather than bowed as it typically is in classical music. Classical orchestras feature woodwinds, brass, and percussion but also include bowed string instruments such as the violin, viola, and cello, which are rarely used in jazz. There are typically anywhere from 50 to 100 musicians that make up a classical orchestra. As another example of the differences in instrumentation, a piano trio in jazz typically consists of a piano, upright bass, and drums whereas in classical music it typically consists of a piano, violin, and cello. The piano is a central instrument of both classical and jazz.
Jazz musicians also play their instruments differently than classical musicians do, sometimes using slurs and "dirty" sounds that create tone colors distinct from what one usually hears in classical music. The composer George Gershwin, who was influenced by early jazz, wrote a famous clarinet glissando at the beginning of his Rhapsody in Blue that imitates the "dirty" sound of jazz.
Historically, jazz musicians have usually performed in more casual venues such as nightclubs or hotels or specialized jazz clubs. Classical players usually perform in more formal settings, such as a concert hall or amphitheater. Over time, though, jazz has increasingly moved into concert halls and other more formal settings as well. The famous jazz clarinetist Benny Goodman played Carnegie Hall back in 1938. Today, jazz, like classical music, is taught in universities and conservatories and considered by many to be "serious music."
Classical music traces its roots back to the 11th century, to Gregorian chants and plainsong developed from monodic (written as one musical line) to organum (two or three lines moving simultaneously but independently, bringing out harmony). By the fifteenth century, composers began writing choral music and adding instrument compositions to the lines of music. Since the Renaissance, the history of classical music is usually divided into baroque, classical, Romantic, modern, and post-modern eras. New Orleans is where jazz originated in the late nineteenth century, created principally by the descendants of freed African slaves. Jazz evolved from dixieland, ragtime, blues, marches, and other influences, including classical music. Its major historical periods include swing, bebop, and post-bop.