Adding printers to OS X is a fairly straightforward process in which you go to the Print & Scan (or Print & Fax) system preferences and click the plus symbol in the printer list to add a printer. In many offices or even homes, printers may be available in separate locations, which you can add to your printer list so they will be available for your system. With multiple printers installed, you can select the desired one from the Printer drop-down menu when you invoke the print command in a program.
This setup is a fairly standard way of managing printers. If multiple printers are available in a given location--as in an office where you might have a separate printer in one room, and also a bank of printers available in a main print center--adding these printers to your system is done in the standard way by using the Print & Scan system preferences. If you print to them then again you will have to specify the desired one to print to.
Setting up a bank of printers in this manner has its inconveniences, especially in situations in which you need to print numerous separate print jobs or multiple people submit print jobs. In these situations, one printer can end up queueing several print jobs while others sit idle.
To tackle this problem, OS X supports lumping printer devices together as a virtual device called a printer pool. The pool acts as a dispatch agent for the collection of printers that it represents, so when you submit multiple print jobs to the pool, it will print them on whatever device is available, as opposed to queueing them all up on one device or requiring you to select a specific printer for each print job. This means that if you regularly submit multiple print jobs to your printers, you can set them all up as a single device for your computer to print to, so that your print jobs can get done as quickly as possible.
Creating a printer pool in OS X is a fairly simple process:
Install your printers
The first step is to get your printers installed on the system if they aren't already, so add each one by clicking the plus sign at the bottom of the list in the Print & Fax system preferences. Make sure they are set up properly by printing a test page on each.
Select the pool printers
Press the Command key on your keyboard and click the various printers in the list that you wish to have in the pool. With the command key held down, you can click a printer to add or remove it from the selection.
Create the pool
When you have more than one printer selected, the Print & Fax window will change to a button for creating a printer pool. When you have your desired printers selected, click the button and name the pool when prompted.
At this point the printer pool will show up in the printer list, and will have a queue of its own. Unfortunately you cannot add or remove printers from the pool once it is created, so to change the pool you will need to delete it and create a new one. You also cannot create a pool that contains other pools, so for instance to create a pool for all of your printers, you will have to select all printers and then deselect any current pools you have before creating the pool.
As with regular printers, you can share the printer pool on the network, which may be an easy way to propagate the pool to other systems since they just have to add the shared system instead of setting up the printer pool on each system. This could be particularly convenient if you have a dedicated Mac that can serve as a print server for both USB and networked printers.