Jazz is a music genre that originated in the African-American communities in the early 20th century. The Jazz age occurred during 1920 - 1930 i.e, started post-World War 1 movement and ended with the Great Depression in 1929. It was the age in which jazz music and dance emerged.
In batched operating system the users gives their jobs to the operator who sorts the programs according to their requirements and executes them. This is time consuming but makes the CPU busy all the time.