What is a Post Office Flyer or Announcement?

Most countries issue a flyer that contains the technical information for each new issue that comes out.  The format varies from country to country as does the actual information contained within the announcement, but typically, include the following:  an illustration of the stamp and the first day postmark; date of issuance, quantity printed, face value of the stamp, printing method, etc...

In addition, there is usually a narrative about the reason the stamp was issued.  In the example shown below, I chose a 2013 issue from Chile to honor the 125th Anniversary of the Philatelic Society of Chile.  There is a brief history of the organization and why it was chosen by the Chilean post office to be honored.

Front side of a typical Post Office Announcment

Inside of a typical Post Office Announcement