Background jobs in SAP system run in the background without affecting normal operations in the system. These jobs are used to reduce manual effort and to automate the process. They can run in the background without any user input and can be scheduled to run when the system load is low.
Background jobs can be divided into three categories −

Class A (High Priority)

This is used for urgent or critical tasks and must be scheduled with class A priority job. Class A job reserves one or more background work processes.

Class B (Medium Priority)

These jobs are executed after the completion of high priority jobs of Class A.

Class C (Low Priority)

The jobs in this category run once class A and class B jobs are completed.
Transaction Code SM36

General Data

Enter the Job Name and its Priority.
Select the target server on which you want to execute the job. This is used for load balancing; you can define the target server on which you want to run the job.
Define Background
Using Spool List Recipient, enter the email id if you want to get the results in email.
To define the steps for execution, go to the Step Tab. Enter program name, variant name in the field. If you have not created variant as per your requirement, then leave it blank. Click on the save button at the bottom.
Create Step 1List Overview
To pass the start condition, enter the start date, end date, frequency, etc. In case the start condition is not specified, then the job will remain in scheduled state and will not run. Various options can be used to define the start condition. To create a periodic job, select the box at the bottom.
Background Job
Once the schedule is defined, click on Save.
Schedule is Defined