Commemorative stamps are usually issued on a special date or anniversary to commemorate a place, person, object or event. The subject of the stamp is usually identified in print on the stamp. Commemorative stamps are printed in limited quantities over a short period of time. Many postal services issue commemorative stamps throughout the year and they can be used along with other types of stamps. A collector can learn about the geography, wildlife, important people and events and history of a country by studying the postage stamps issued by a country.