in many countries, set of stamps are used to commemorate events, such as anniversaries of a persons birth. in the uk. only members of the royal family or the entire groups, such as sports team, may appear on stamps....
there are a few factors that govern how valuable a stamp is to stamp collectors; the most importan is how rare it is, obviously very old stamp are uncommon so these, such as the penny black! ver seldom come up for sale and and so are unbelievably expensive.
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other things that make a stamp rare might be where mistake was made in the printing and the stamp was withdrawn after only few had been sold. undamaged stamps are more valuable thatn similar ones that have benn damaged...
i hope you like my research thank you very much:)