An item of mail on which nothing appears on the right side of the face except the name and complete address of the addressee and such postal endorsements or labels as are necessary to facilitate delivery of the postcard. The postage must be affixed in the upper right-hand corner of the address side. (carte postale)
Postcards get a special "post card" rate from the USPS. A postcard may be no larger than 4.25" x 6" (minimum size is 3.5 x 5") and at least .007 inches thick. It must be rectangular in shape. Special 1st class presort rates are also available. There is no special, nonprofit rate for post cards. NOTE: Double postcards do not fall into this category.
A commercially printed card with space on one side for an address and a postage stamp. Used for sending a short message through the mail as well as a cost effective method of advertising a business or service.