In philately, private overprints or commercial overprints are overprints applied to postage stamps, postal stationery or revenue stamps by anyone other than the official stamp-issuing entity. These overprints have principally been used as a security measure,[1] however, propaganda and commemorative examples are also known. When overprinted for security purposes, they serve a similar function to perfins. It is important to distinguish between private overprints and private cancellations.
- ^ Sutton, R.J. & K.W. Anthony. The Stamp Collector's Encyclopaedia. 6th edition. London: Stanley Paul, 1966, p. 195.