Philately has come to mean, specifically, the collection and study of postage stamps, postmarks and stamped envelopes and the study of postal history. A cachet is a design placed on an envelope, usually commemorating the event for which the cover, as that envelope is known, is being prepared. For first day covers, the design is usually closely related to the subject of the newly issued stamp. The cachet usually appears on the left side of the envelope.
Stamp hinges are thin rectangular pieces of paper which are used to hold stamps in an album.
One side of each hinge is coated with a special adhesive that becomes sticky when it is slightly moistened. Hinges may be purchased from stamp dealers or hobby stores. Hinges come in two varieties, flat and pre-folded. Coil stamps are stamps made for use in vending or affixing machines and are sold in rolls. The other sides of the stamps are cut straight.