Thermal transfer printers use colored waxes and heat to produce images by burning dots onto special paper. The colored wax papers are not required for black-and-white output because the thermal print head will register the dots on the paper. For people who want the highest-quality color printing available with a desktop printer, thermal printers are the answer. However, they are expensive, and they require expensive paper. Thus, they are not generally used for jobs requiring a high volume of output.
It is not uncommon these days to receive a crisply printed letter rendered on a word processor in an envelope with a handwritten address. Why? Because the person writing the letter does not have, or doesn’t know how to use a printer envelope feeder for printing addresses. Envelope feeders and label printers are only one of several considerations to make when buying a printer. (Specially printers are also available, useful for businesses that do large mailings, that print nothing but envelops and labels.)