Microsoft Windows SharePoint Services (WSS) and its Portal version, Microsoft Office SharePoint Server (MOSS), carries out various automatic, scheduled jobs to realize repetitive tasks in a standard way.
The SharePoint Timed Jobs infrastructure takes care of the scheduled tasks needed to ensure proper functioning of the system. Timed Jobs run in the background and are based in the Microsoft SharePoint Timer service, which is always installed in the default setup of WSS and MOSS. Installed Timed Jobs can be configured from SharePoint's Central Administration using the Command-Line administrator's tool or programmed using the Object Model.
Timed Jobs can be set up to run immediately or in a time frame based on "one," meaning a SharePoint Job can run each minute, day, or week but not, for example, every two hours or days. Another limitation is that it is impossible to schedule Jobs to run on relative time frames; for example, the second Monday of every month. A Timed Job requires a starting time, and the configured time frame determines the interval it will run at. The starting time can be an absolute time (at 12:00 am, for example) or a time range (between 8:00 and 9:00 am); in the first instance, the Job would require a few seconds to execute because the service needs to be initiated; in the second case, the Job will run at a random time within the range, giving the different servers in the farm the opportunity to progress at varied periods, balancing the load on the system.