CUPS is a standards-based, open source printing system developed by Apple Inc. for macOS® and other UNIX®-like operating systems. CUPS uses the Internet Printing Protocol ("IPP") and provides System V and Berkeley command-line interfaces, a web interface, and a C API to manage printers and print jobs. It supports printing to both local (parallel, serial, USB) and networked printers, and printers can be shared from one computer to another, even over the Internet!
Internally, CUPS uses PostScript Printer Description ("PPD") files to describe printer capabilities and features and a wide variety of generic and device- specific programs to convert and print many types of files. Sample drivers are included with CUPS to support many Dymo, EPSON, HP, Intellitech, OKIDATA, and Zebra printers. Many more drivers are available online and (in some cases) on the driver CD-ROM that came with your printer.
CUPS is licensed under the Apache License Version 2.0. See the file "LICENSE" for more information.
Full changelog available here.