A peninsula on the southern coast of Arabia, Aden was formerly part of the Indian Empire. It was a Crown Colony from 1937 to 1963 when Aden joined the South Arabian Federation whose stamps it then used.
See all Aden stamps in the StampWorld free online catalogue.
Scanned album pages from the worldwide stamp collection of Antonius Ra.
An overview of Aden stamp issues, on the Stamps of Distinction site.
Wikipedia page providing a useful introductory overview of the stamps and postal history of Aden.