the unit of a printing press from which <#stamp=stamps> are actually printed. 19th and early 20th century stamps were produced from <#flatplate=flat plates>. Beginning in the mid-1920s most stamps were produced from curved (180º) plates that were used in pairs on a <#rotpress=rotary press>. Still more recently, many stamps have been printed from <#cylinder=cylindrical> plates. A plate is sometimes also known as a printing base.