Postal Stationery

A letter sheet made of a single sheet of lightweight paper with gummed flaps, normally used for international airmail.
When folded and sealed, the message is on the inside and the outside resembles an envelope on which a stamp has been printed, usually at a rate slightly less than the first-class air letter rate.

An envelope with a stamp pre-printed or embossed in the upper rifht hand corner is called a stamped emvelope.
When you buy the envelope you pay the cost of the stamp and the envelope.

A card with a stamp printed in the upper right hand corner is known as a postal card.
The address goes on the stamp side, while the writing usually goes on the opposite side.
The postal card shown above was cancelled on June 23, 1893.