Stamp hinge

In philately, stamp hinges, or mounts, are small, folded, transparent, rectangular pieces of paper coated with a mild gum.

The hinge keeps the stamp on the page while still allowing it to be lifted to examine the back, for instance to see the watermark or expert marks.

Some old stamps may have multiple hinge remnants layered on top of each other.

Conversely, careless removal of a hinge may take away a layer of the stamp's paper, resulting in a type of stamp thin known as a hinge thin.

While this was formerly a matter of indifference, since about the middle of the 20th century many collectors have come to prefer "unhinged stamps" showing no trace of hinging.