Computer printers, or more commonly a printer, produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper or transparencies. Many printers are primarily used as local computer peripherals, and are attached by a printer cable to a computer, which serves as a document source. Network printers, have built-in network interfaces (typically wireless or Ethernet), and can serve as a hardcopy device for any user on the network. Individual printers are often designed to support both local and network connected users at the same time.

In addition, many modern printers can directly interface to electronic media such as memory sticks or memory cards, or to image capture devices such as digital cameras or scanners; some printers are combined with a scanners and/or fax machines in a single unit (All In One Printers). Printers that include non-printing features are sometimes called Multi-Function Printers (MFP) or Multi-Function Devices (MFD). A printer which is combined with a scanner can also function as a photocopier. Most MFPs include printing, scanning, and copying among their features. Many of today's printers no longer need cables to connect to the computer, and can connect via wireless networks.

Printers are categorized by the technology used to produce the image on the page: Laser Printers, InkJet Printers (also Photo Printers), Dye Sublimation Color Printers, Dot Matrix Printers from makers such as Okidata, Label Printers, Impact Printers, Thermal Printers, Receipt Printers and Point of Sale Printers, Bar Code Printers, and specialized printers such as CD Label Printers.

A laser printer rapidly produces high quality text and graphics on plain paper. Like photocopiers, laser printers employ a xerographic toner printing process but differ from analog photocopiers in that the image is produced by the direct scanning of a laser beam across the printer's photoreceptor.

Inkjet printers operate by propelling various size (mostly tiny) droplets of liquid or molten ink onto almost any media. They are the most common type of computer printer for the general consumer due to their low cost, high quality of output, capability of printing in vivid color (such as Photo Printers), and ease of use.

Other categories of products related to printers are: Shredders, Binders, Laminators, Scanners and Fax Machines.