A printer driver is a software program that allows a computer to communicate with a printer. It translates the data from the computer into a format that the printer can understand, ensuring that documents are printed correctly. Without the appropriate driver, the printer may not function properly or may not be recognized by the computer. Printer drivers are specific to both the operating system and the model of the printer. Users can usually download the correct driver from the manufacturer's website. Keeping the driver updated is important for optimal performance and compatibility with new software or operating systems.