The content of this page is a public resource and may be distributed freely if unchanged and credited to the author. Below, I will discuss the different uses to which stamps are put, the standards by which stamps are graded, the best way to handle and store stamps, and other collecting topics.
Airmail stamps can occur as definitive or commemorative issues.
They're usually pretty or elaborate or appealing in some way, to commemorate their subject. They're sold for a limited time. They are reprinted often. The US Christmas stamps that come out every year are special stamps. WWII produced many occupation stamps.