An Acronym for Internet Printing Protocol.
The most commonly used implementation of IPP on Linux is called CUPS.
A protocol designed to easily allow computers to communicate both with IPP-enabled printers, and with other computers acting as print servers.
Recent versions of MicrosoftWindows as well as MacOSX also understand and support IPP.
IPP uses port? 631 (listed in services(5)) - you can also talk to a print server via HTTP. For example, if your workstation is using CUPS you can point a WebBrowser at 
http://localhost:631/ to see the available printers on your local machine. (These include remote printers and print servers that your local machine is set up to use).
