A thermal transfer printer is a printer

Computer printer

In computing, a printer is a peripheral which produces a text 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 peripherals, and are attached by a printer cable or, in most new printers, a...

 which prints on paper

Paper

Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....

 (or some other material) by melting a coating of ribbon so that it stays glued to the material on which the print is applied. It contrasts with direct thermal printing where no ribbon is present in the process. It was invented by SATO corporation around the late 1940s

Usage of TT printers in industry includes:

• barcode
  Barcode
  A barcode is an optical machine-readable representation of data, which shows data about the object to which it attaches. Originally barcodes represented data by varying the widths and spacings of parallel lines, and may be referred to as linear or 1 dimensional . Later they evolved into rectangles,...
  
   labels (as labels printed with thermal printer
  Thermal printer
  A thermal printer produces a printed image by selectively heating coated thermochromic paper, or thermal paper as it is commonly known, when the paper passes over the thermal print head. The coating turns black in the areas where it is heated, producing an image...
  
   tend not to last long), or for marking clothing labels (shirt size etc.)
• Printing plastic labels for chemical containers (because the cheaper types of plastic would melt in a laser printer)

Barcode printers typically come in fixed sizes of 4 inches, 6 inches or 8 inches wide.