A postcard is piece of thick paper or thin cardboard, typically rectangular and today often in the paper size A6, that has a photograph or print of a drawing or painting on one side (the front). The reverse side is used to write a personal message and a recipient's address, and to stick a stamp on, for sending by mail.
A postcard is similar to a letter, but with minimal space for the message and no envelope to hide the message from other eyes. The main purpose of postcards is to send someone a short greeting, e.g. from a vacation trip.
 Spanking art on postcards
- Main article: spanking postcard
Humorous spanking drawings (cartoons) and photographs are sometimes published on postcards. Spanking postcards were particularly popular in the first half of the 20th century, with pun captions such as "I'm getting tanned" or "I guess I'll have to bare it". They were usually in the sub-genre of cartoon child spanking art.