Standard
background jobs 
Use
Standard jobs are jobs that should run regularly in the SAP System. They usually "clean-up" parts of the system. As of Release 4.6C, transaction SM36 (Defining Jobs) provides you with a selection of standard jobs.
Effects on System Administration
Using the new functions, you can easily schedule standard jobs from the selection. You can also define other jobs as standard jobs.
See also
For more information, see the SAP Library.