South Australia began using its own stamps in 1855. These featured portraits of Queen Victoria, and followed the imperial monetary system of pence, shillings, and pounds, as did the other territories that eventually became the Commonwealth of Australia in 1901. South Australia issued stamps until 1912.
South Australia used overprints often on their stamps to denote postal value. Also of interest to Australian overprint stamp collectors are the several departmental ‘official stamps’ of South Australia, with ‘OS’ or other 1- and 2-letter overprints to indicate the governmental department of use.
There were also several revenue stamps used in South Australia. Later South Australian stamp collectibles include modern Australian stamps with subjects relating to South Australia, which can include covers (and first day covers), maximum cards, and souvenir sheets. Check the listings often; they are updated daily.