Print Spooling means to send jobs to a print queue for processing so the printer and CPU can process other tasking before printing the data being held in the spooler. A print spooler manages the print process and can have a variety of duties managing printing pools, tracking which job went to what printer, shared and network printers, keeping track of what device is connected to what port.
Spooling prepares a file (usually a data file) for printing, emailing, faxing, or sending to a device or system that is currently occupied with another task. Spooling can also be called a "print scheduler", the boss of all printing functions within a device or PC. Maintaining current readiness to printers, which printers are located on the network, IP address, sending jobs to the LPD line printer daemon, etc.
Print spooler software will print the document to the actual device (or printer) when the printer is ready. This allows the PC / printer to concentrate on more important tasks. In addition, system resources on your network servers are freed up, allowing your server to concentrate on other tasks and letting your LPR print spooler do all the work! Click on the link for more information on spooling.