SPOOL, short for Save Printing Operation On Line, is a computer process that temporarily stores print jobs in a queue while waiting for them to be sent to the printer. When multiple photographs or documents are sent to print in succession, any files not immediately processed are held in this queue until the printer is ready to handle them.
Spooling improves efficiency by allowing the computer to continue working on other tasks instead of waiting for each print job to finish individually. In photography and graphic design workflows, this is particularly useful when printing large batches of images, proofs, or contact sheets, as it helps manage multiple print commands smoothly and ensures files are output in the correct order.