Revenue stamps are also known as Tax, Fiscal or Duty stamps. They collect the fees or taxes due on official documents, hunting or firearms licences, tobacco and alcohol, medicines, playing cards and many other items. Very often they are similar to postage stamps, and many stamps are dual-purpose, i.e. may be used for both postage and revenue purposes. Historically, they were once as popular as postage stamps, but fell out of favour for much of the last century, prior to a revival of interest, with Revenue collections now winning high awards at National and International exhibitions. This is a very big subject with much still to discover!