* Postal stationery products are popular among some collectors. These have the stamp designs printed or embossed (printed with a raised design) directly on them.

* Stamped Envelopes were first issued in 1853. More than 600 million of them are now printed each year.

* Postal Cards were first issued in 1873. The first U.S. multicolored commemorative postal cards came out in 1956. Several different postal cards are issued each year.

* Aerogrammes (air letters) are designed to be letters and envelopes all in one. They are specially stamped, marked for folding and already gummed.