Stamp issued specifically to prepay postage for mail carried by air.
Block
Four or more attached stamps forming a square or rectangle.
Booklet Panes
Small, specifically-printed sheets of stamps sold in a booklet format.
Cancellation
Any mark applied to a stamp to prevent its reuse.
Commemorative Stamp
Stamp issued specifically to honor a person, place or event; usually on sale for only a short period of time.
Cover
An envelope, postcard or any other wrapper used to mail correspondence.
Denomination
The monetary value printed on a stamp.
Never Hinged
The stamp has never had a hinge applied to it. Never Hinged has an expanded meaning though, the gum must be in like new condition with no marks of any kind whether made by a hinge or by something else.
Postmark
Marking on a postal item recording the date and/or origin of its transit through the mail system.
Revenue Stamp
Any stamp that indicates payment of a tax or fee.
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