The stamp’s shape is usually that of a small rectangle of varying proportions, though triangles or other shapes are occasionally used. The stamp is affixed to an envelope or other postal cover (i.e., packet, box, mailing cylinder) that the customer wishes to send. The item is then processed by the postal system, where a postmark, sometimes known as a cancellation mark, is usually applied over the stamp and cover; this procedure marks the stamp as used, which prevents its reuse. The postmark indicates the date and point of origin of the mailing. The mailed item is then delivered to the address that the customer has applied to the envelope or cover.