A postcard or post card's a rectangular piece of thick paper or thin cardboard intended for writing and mailing without an envelope and at a lower rate than a letter. Stamp collectors distinguish between postcards (which require a stamp) and postal cards (which have the postage pre-printed on them). While a postcard's usually printed by a private company, individual or organization, a postal card's issued by the relevant postal authority. The United States Postal Service defines a postcard as:… (More on Postcard)