Spooling works like a typical request queue or spool where data, instructions and processes from multiple sources are accumulated for execution later on. Generally, the spool is maintained on the computer’s physical memory, buffers or the I/O device-specific interrupts. The spool is processed in ascending order, working on the basis of a FIFO (first in, first out) algorithm.

The most common implementation of spooling can be found in typical input/output devices such as the keyboard, mouse and printer. For example, in printer spooling, the documents/files that are sent to the printer are first stored in the memory or printer spooler. Once the printer is ready, it fetches the data from that spool and prints it.