Printheads are a key component for printing quality barcode labels and ID cards. A printhead uses heat that is applied to whatever surface that is being marked. For example, with thermal transfer printing, the printhead applies heat to a ribbon, which is then applied to the label that is being created. If it is direct thermal printing (which does not utilize a ribbon), the printhead applies heat to a label which then "darkens" the appropriate portions.

Printheads can print in a variety of densities which is measured in dots per inch (DPI). In barcode label printing, printheads typically come in 203 dpi, 300 dpi, and 600 dpi versions. Depending on what one wants to print will determine which density of printhead to use. For instance, most barcode label printers print at a density of 203 dpi because they are typically dping "text-only" printing ; if you want to add graphics to the label, a 300 dpi is preferred (which is also why most ID card/badge printers utilize printheads with a density of 300 dpi). 600dpi printheads are used where high-density printing is required such as those labels that will be applied to printed circuit board.