The music known today as jazz has gone through many different changes in the last two centuries. Begun as an off-shoot of ragtime in the late 1800's, it traces its roots back to the end of that century. This music was originally played by small bands in New Orleans nightclubs. Ragtime musicians in that city experimented until they found a sound that fit their lifestyle and audience.
While it has never died off, jazz has been through a number of revivals that have transformed it. The classic jazz of New Orleans has grown branches and been revived several times. Hot jazz is one of the earliest off-shoots of the original classic jazz. Dixieland is a revival form of classic jazz as it was originally played but with a modern style. Mainstream jazz is both an off-shoot of classic jazz as well as a revival of swing.