Thermal transfer
A printing method where a heated printhead melts wax or resin off a ribbon onto the media.
It differs from direct thermal, which darkens heat-sensitive paper with no ribbon at all and therefore fades in sunlight and warmth. Here a single-use ribbon carries the pigment, and the printhead's row of dots melts off precisely the ones that should become text or bars. The image lasts for years, which is the entire point of barcode labels, shipping tags, and ingredient stickers meant to survive a cold store.
The method broke through in the 1980s with firms like Zebra and SATO and became the standard for industrial labelling. Wax suits paper, resin suits plastic film, and a wax–resin blend sits between. One thermal printer can often run either mode depending on the ribbon loaded.