Ersttag
Ersttag is a term with German origins, meaning "first day." It is most commonly used in philately, the study and collection of postage stamps. In this context, an Ersttag or first day cover (FDC) is an envelope or card that has been posted and bears a postage stamp that has not yet been officially released for sale to the general public. The stamp must be canceled on its first day of issue.
The concept of the first day cover originated in the late 19th century. Collectors began to recognize
Special events, anniversaries, or the introduction of new postal services can all be commemorated with the