There are various categories of stamps. Here are some of them:

v     Origin  :  issued countries

§         It refers to the place which issue stamps, e.g. USA, United Nations, PRC, Germany, etc.

§         It is usually the primary classification in the stamp catalogues, e.g. Scott, Stanley Gibbon, Michel, etc.

v     Topic  : 

§         It refers to the theme of the stamp, e.g. animals, transport, Christmas, flag, New Year, Europa, etc.

§         The most common topics are the animals, Christmas, flowers, etc.

§         There are some stamp catalogues are specialised in some of these topics

v     Format  : 

§         It refers to the presentation of the stamps.

Ø      Single or Set: the stamps are issued in single stamps or in set

Ø      Miniature sheet: the stamps are placed enclosed in a small sheet

Ø      Souvenir sheet:  a whole sheet consists of different  stamps

Ø      Se-tenant: a set of stamps attached to each other in a strip

Ø      FDC (First Day Cover): the stamps are placed and stamped on a cover.

Ø      Booklet: the stamps are placed inside a booklet

Ø      Presentation Pack: the stamps are stored in a pack, which includes full description of the stamps

Ø      Coil: the stamps are issued in a coil.

v     Type  : 

§         It refers to the purpose of the stamps.

Ø      Commemoratives: the stamps are issued for specific issues, e.g. Christmas, Anniversary, etc., which can be available at the office for short period of time.

Ø      Definitive: the stamps are issued for mailing purpose, which can normally be available at the post offices for more than one year.

v     Condition  : 

§         It refers to the physical conditions of the stamps.

Ø      U/M (**) – un-mounted mint: the stamp new and has not been mounted

Ø      Hinged (*) – the stamp has been hinged

Ø      U – the stamp has been used and stamped

Ø      CTO – the stamp has been stamped on its issue

Ø      F – Fine: the stamp is in fine condition

Ø      VF – Very Fine : the stamp is in very fine condition

Ø      Gum – the stamp has some dirt

v     Shape  : 

§         It refers to the appearance of the stamps.

Ø      Rectangle

Ø      Round

Ø      Triangle

Ø      Trapezoidal

Ø      Diamond

Ø      Irregular

v     Printing  : 

§         It refers to the printing method of the stamps.

Ø      Texture – the surface of stamp is uneven caused by the ink, usually old stamp of single colour, e.g. Bahamas, Fiji and other old British Commonwealth stamps.

Ø      Flat  – the modern stamps with the flat and smooth surface

The above classifications are not comprehensive and are only based on my experiences.

Book 1  Topical  Favourite  Classifications Format  Shapes