A used stamp, souvenir sheet, postal stationery item or miniature sheet is one that genuinely passed through the postal system and was properly cancelled as evidence of postal use or payment of postage.

Common catalogue and marketplace notation: ⊙ or U (used).

Used stamps are generally catalogued at lower values than mint never hinged examples, but there are many exceptions. In some cases, genuinely postally used, and therefore actually used in the postal system, examples are scarcer and more valuable. This may apply to high-surcharge issues produced mainly for collectors or to stamps that were withdrawn after only a short period of postal validity.

Strictly speaking, only stamps that actually passed through the postal system should be described as used. Stamps that were cancelled but never used on a postal item are known as CTO (cancelled to order) or favour-cancelled examples.

Distinguishing CTO from genuine postal use is sometimes straightforward. Undisturbed original gum, a completely cancelled sheet or a mechanically printed imitation cancellation can provide obvious clues. In many cases, however, genuine postal use can only be confirmed by examining the entire postal item, such as the cover on which the stamp remains.

For this reason, catalogues often do not assign separate basic values to CTO and genuinely used stamps. On certain issues, however, they specifically note that genuinely postally used examples are much scarcer and should command a premium.

The cancellation itself can also increase a stamp’s value. A rare post office mark, first-day use, unusually late use or another unusual postal-history feature may add substantial value.

Hungarian philatelic literature contains extensive research on postmarks. On classic issues in particular, the place of use and the type of postmark can be extremely important. A rare, attractive and clearly struck cancellation may be worth several times the basic value of the stamp.

Austrian stamps used in Hungary between 1850 and 1867 are collected under the field of “Austrian Post in Hungary” when they bear a cancellation from a Hungarian post office. Examination of the postmark is therefore particularly important on these issues.