A dot matrix printer is an impact printer that prints using a fixed number of pins or wires. Typically the pins or wires are arranged in one or several vertical columns. The pins strike an ink-coated ribbon and force contact between the ribbon and the paper, so that each pin makes a small dot on the paper. The combination of these dots forms a dot matrix image. They were also known as serial dot matrix printers.

While inkjet and laser printers technically exhibit dot matrix printing, they work differently than impact "dot matrix printers" and can deposit ink or toner at higher dot resolutions more quickly, with less inherent noise. The impact printer has the ability to make copies using multi-part forms, unlike an inkjet or laser printer.