WHAT ARE FDC AND MC BIG PACKS?

Are envelopes affixed with a stamp or stamps on the first day that they are made available for sale to the public. On the first day of issue, the envelope is stamped with a postmark and cancellation indicating the date and location that the envelope was received into the postal service

On occasion, the postmark and cancellation are joined and form one continuous design: the postmark is the circular mark the cancellation is the horizontal bars that are applied directly onto the stamp.

Souvenir or Commemorative Covers can be confused with First Day Covers, as they may look similar. There is an important difference. First Day Covers are issued on the same date as the new postage stamps. Souvenir Covers are generally issued to mark the date of a special event or anniversary.