Handstamp: The implement used to apply a postmark by hand, but often used loosely to signify the postmark itself. Many overprints and control marks were applied by means of handstamps. In other words we can say, Cancellation or overprint applied by hand to a cover or to a stamp.
Head Post Office (HPO): In India Head Post Office – main post office.
Highway Post Office (HPO): Portable mail-handling equipment for sorting mail in transit on highways (normally by truck, in U.S.).
Hinge: A small piece of paper or glassine used to attach a stamp to an album page. Most modern hinges are peelable. Once dry, they may be easily removed from the stamp, leaving little trace of having been applied.