A rubber stamp is an image or pattern that has been carved, molded, laser engraved or vulcanized onto a sheet of rubber. Rubber stamping, also called stamping, is a craft in which some type of ink made of dye or pigment is applied to rubber stamp. A rubber stamp is normally used to imprint a name, date, or symbol of some sort.

You press it on to an ink pad and then on to a document in order to show that the document has been officially dealt with.