With the superficial view of the various issues of postage stamps, it can be concluded that they can be grouped into different groups. The details are explaining the division of stamps according to four criteria, although there are other criteria. The most important division of stamps is the purpose and type of traffic for which they are used, because in this way they are characterized in catalogs. Visit APF website at http://americanphilatelic.com/ and learn more about their appraisal services.