Printer Pooling allows two or more identical printers to be installed as a single logical printer, allowing the print load to be spread across a pool of several printers. It can be cheaper to run two small printers rather than a single large one and there is some backup if one of the printers fails.
Configuring Printer Pooling is very straightforward, you start by configuring the first printer as a standard Windows printer. Then by using the Ports tab of the Printer Properties you can check the Enable Printer Pooling option at the bottom of the dialog box. This will allow you to add and select ports for each of your additional printers.
If all the printers you are adding to the pool are the same make and model then it really is as simple as this, however if you are using different models or even makes of printer then you will need to think about which printer driver to use. Most printers are backwards compatible with previous similar models so selecting the driver for the oldest model of printer in your pool will probably work, eg: if you have a pool of printers consisting of an HP LaserJet 4 and an HP LaserJet 5 then using an HP LaserJet 4 driver will produce data compatible with both printers. There may be some combinations which just will not mix, eg: an Epson inkjet and an HP laser printer. These two devices have distinct data streams which are not compatible with each other.
By default the output will go to the first printer in the pool unless that printer is unavailable, in which case it will go to the next available printer. This obviously isn't sophisticated enough for many applications as one printer will get all the wear and tear. For a more sophisticated solution you will need to look at 3rd party software.