Postal stationery
A piece of postal stationery is a stationery item, such as a stamped envelope, letter sheet, postal card, lettercard, aerogram or wrapper, with an imprinted stamp or inscription indicating that a specific rate of postage or related service has been prepaid. It does "not", however, include any postcard without a pre-printed stamp, and it is different from freepost for preprinted cards issued by businesses. Format and origin. In general, postal stationery is handled similarly to postage stamps; sold from post offices either at the face value of the printed postage or, more likely, with a surcharge to  cover the additional cost of the stationery. It can take the form of an official mail issue produced only for the use of government departments. It can be an issue of a military force where an army, perhaps in a distant war, issues letter sheets for the use of its troops to write home. Postal stationery can be overprinted by the government or, occasionally, by a private overprint. In emergency situations, postal stationery has been produced by handstamping envelopes with modified canceling devices; many of the rare Confederate postmasters' provisionals are of this form. Finally, some postal stationery can be  printed to private order. In this last case, stamped stationery bearing indicia is applied with postal administration approval and with specified regulations, to paper or cards provided by private persons or organizations. Private impressions result in a wider range of denominations and designs compared with governmental issues. Types. Aerograms. The postal services of some countries also offer a form of letter sheet called an aerogram consisting of a blank sheet of paper with folding instructions and adhesive flaps that becomes its own envelope, and carries prepaid postage at either the international airmail letter rate or at a special lower aerogram  rate. Letter sheets lend themselves to airmail usage because they are lightweight. Enclosures are not permitted in aerograms. Sales of aerograms in the United States ended in 2006 due to poor sales. Letter cards. A letter card almost has the advantages of a postal card as far as weight and size, but also the advantage of privacy of contents is concerned. It is a double card, folded over, with gum or adhesive applied to the three open edges. It is then opened by the recipient by tearing perforations on the three sides that are on the message side of the  gum. The gummed strip around the card is then discarded, giving rise to the problems collectors have in finding intact used cards. The US has never issued any letter cards. Letter sheets. Before 1845 correspondence was not enclosed in an envelope. Letters were folded, sealed, addressed and postmarked on the outside. This continued even after adhesive postage stamps were introduced. The popularity of folded letters led postal authorities to introduce stamped letter sheets. These became available in the U.S. in 1861, but the first official postal stationery were the 1838 embossed letter sheets of New South Wales. These were followed  by the Mulready stationery that was issued by Great Britain at the same time as the Penny Black in 1840. Since then, most postal services have issued a steady stream of stationery alongside stamps. Often the design of the stationery mimics the contemporaneous stamps, though with less variety and lower printing quality, due to the limitations of printing directly onto the envelope. Much later, 1947 in the U.S., letter sheets morphed into lithographed air letter sheets or aerograms. Postal cards. Postal cards are postal stationery and have a printed or embossed indicium and are sold by governmental postal authorities. In  the United States, they were first produced in 1873. Some of the forms taken by postal cards include the regular single card, the attached message-reply cards, airmail postal cards, and official postal cards used for official government business with a "penalty for private use". Postcards, on the other hand, are cards prepared by private companies that do not have prepaid franking and readily available at commercial outlets. They are frequently illustrated with pictures or printed advertisements. They are generally "not" considered postal stationery. Registered envelopes. A strong envelope with an imprinted stamp sold only for use with the registered  mail service. Confusingly, these are usually marked "Registered Letter" but that term strictly only relates to a normal letter or packet that has extra postage and markings applied so that it may travel under the registered mail service. Stamped envelopes. The envelope form may be called a stamped envelope or, alternatively, a postal stationery envelope (PSE for short). In August 1852 an act of the U.S. Congress authorized the Postmaster General to provide "suitable letter envelopes with such watermarks or other guards against counterfeits... with the addition of the value or denomination of the postage stamps so printed or impressed  thereon...". The first result was the 1853 Nesbitt issues of stamped envelopes, named after the contractor who produced them for the government. Considering the different envelope sizes, knives, colors, dies to print the indicia, and denominations there have been literally thousands of different stamped envelopes produced for the U.S. Wrappers. The manufacture of wrappers for the sending of newspapers or periodicals began in the U.S. in 1861. The first wrappers were rectangular pieces of paper with gum to seal it on one end and an embossed envelope stamp or indicium on it. By 1870, the form was that of a  rectangle with the narrow side rounded and gummed at the top. They were manufactured from piles of 300 - 500 sheets of paper which were then cut to shape by a knife. After around 1900, they were cut individually from long ribbons of paper which had been printed with an embossed envelope die. In the US, they were removed from the items for sale in 1934, though remainders were sold for several years after that. By 1940 most countries had discontinued their production due to declining demand. Because the recipient of a wrapped newspaper often tore it open and threw it  away, untorn used wrappers, preferred by collectors, are scarce. Scarcer yet are wrappers with the original newspaper contents. Because of their larger size, even mint copies are often sold folded or creased which is also less desirable to collectors. Collecting. Most postal stationery pieces are collected as entires, that is, the whole card, sheet or envelope. In the 19th century the practice was to collect "cut squares" (or "cut-outs" in the UK) which involved clipping the embossed indicia from a postal envelope. This destroyed the envelope. As a result, one cannot tell from a cut square what specific  envelope it came from and, many times, the cancellation information. The manner in which the stamped envelope is cut out (defined by the term "knife") vanishes on a cut square. Thus most collectors prefer entires to cut squares. Many country-specific stamp catalogs list postal stationery and there are books devoted to the postal stationery of individual countries. The current, but now dated, principal encyclopedic work is the nineteen volume Higgins & Gage World Postal Stationery Catalog. Societies. Collectors of postal stationery may seek out postal stationery societies or study groups in other countries. These societies provide information, publications and guidance  to those who are interested. They include: