A printer driver, which is a type of Chooser extension, is a software file that Mac OS uses to communicate with a specific kind of printer. It contains information about the printer and instructions for using it. You can't open and read a printer driver, but your computer can.
There are basically two kinds of printers:
A PostScript printer uses PostScript technology developed by Adobe Systems. Inside the printer is a PostScript interpreter, which can process PostScript language commands to print high-quality text and graphics. Examples of PostScript printers include most Apple LaserWriter printers and Hewlett-Packard LaserJet printers.
A QuickDraw printer relies on the computer to send it all of the instructions it needs for printing ...