A duplex printer is a printer that supports printing on both sides of the paper, either automatically or manually. Duplex printing is a cost-saving and paper-reducing way to get the documents you need with less weight, fewer pieces of paper, and less headache-inducing printing issues. A printer duplexer is usually a removable piece of hardware that comes with the printer or can be purchased as an add-on accessory. Besides the hardware itself, many duplexers also need printer drivers, which are downloadable software programs that allow the duplexer to work with your computer and its operating system.

Duplex printing can occur via two different methods, depending on whether or not your duplexer has one or two print engines. With a single-engine duplexer, each page of your print job prints on one side first and then flips over and prints on the other side. A double-engine duplexer means that both sides of the media are printed simultaneously. With this method, a conductor belt generates a picture of both sides of the print job using the data retrieved from your PC. Then, it sends both sides of the page image to one of two transfuser belts that merge and apply toner as pieces of paper slide through the printing device.

In summary, a duplex printer is a printer that supports printing on both sides of the paper, either automatically or manually, and it can be achieved through a removable hardware device called a printer duplexer.