CUPS stands for Common Unix Printing System, is an open source printing system allowing computer to become a print server and manage the printers on the network.
CUPS is the standards-based, open source printing system developed by Apple Inc. for Mac OS® X and other UNIX®-like operating systems. It in essence is a print spooler and scheduler and filtering point to convert the print data into naive format that printer understands. It actually uses 'Internet Print Protocol (IPP)' as the basis for managing print jobs and queues.