The process of temporarily storing documents sent for printing on a hard disk and then sending them to the print device when it is ready (or when some other criterion has been met). The application software that performs this task is called a spooler. The spooler accepts and temporarily stores documents to be printed and then sends them to the printer according to predefined conditions such as print priority and schedule.
Spooling of print jobs allows control to be returned more quickly to the application that generated the job. Spooling also allows jobs to be queued when the printer is unavailable so that the application doesn’t have to generate the jobs again.
The term “spool” is actually an acronym for Simultaneous Peripheral Operation On Line.