Thermal printing

Thermal printing (or direct thermal printing) is a digital printing process which produces a printed image by passing paper with a thermochromic coating, commonly known as thermal paper, over a print head consisting of tiny electrically heated elements. The coating turns black in the areas where it is heated, producing an image.[2]
Most thermal printers are monochrome (black and white) although some two-color designs exist.
Thermal transfer printing is a different method, using plain paper with a heat-sensitive ribbon instead of heat-sensitive paper, but using similar print heads.