A letterhead, or letter headed paper, is the heading at the top of a sheet of letter paper (stationery). That heading usually consists of a name and an address, and a logo or corporate design, and sometimes a background pattern. The term “letterhead” is often used to refer to the whole sheet imprinted with such a heading.
Many companies and individuals prefer to create a letterhead template in a word processor or other software application. This generally includes the same information as pre-printed stationery, but at lower cost. Letterhead can then be printed on stationery (or plain paper) as needed on a local output device or sent electronically. (Info provided by wiki).