Map of Adelaide, SA 5000

Adelaide ( AD-il-ayd, locally [ˈædəlæɪd]; Kaurna: Tardanya, pronounced [ˈd̪̥aɳɖaɲa]) is the capital and most populous city of South Australia, and the fifth-most populous city in Australia. The name "Adelaide" may refer to either Greater Adelaide (including the Adelaide Hills) or the Adelaide city centre. The demonym Adelaidean is used to denote the city and the residents of Adelaide. The traditional owners of the Adelaide region are the Kaurna. The area of the city centre and surrounding Park Lands is called Tarndanya in the Kaurna language.

Adelaide is situated on the Adelaide Plains north of the Fleurieu Peninsula, between the Gulf St Vincent in the west and the Mount Lofty Ranges in the east. Its metropolitan area extends 20 km (12 mi) from the coast to the foothills of the Mount Lofty Ranges, and stretches 96 km (60 mi) from Gawler in the north to Sellicks Beach in the south.

Named in honour of Queen Adelaide of Saxe-Meiningen, wife of King William IV, the city was founded in 1836 as the planned capital for the only freely-settled British province in Australia. Colonel William Light, one of Adelaide's founding fathers, designed the city centre and chose its location close to the River Torrens. Light's design, now listed as national heritage, set out the city centre in a grid layout known as "Light's Vision", interspaced by wide boulevards and large public squares, and entirely surrounded by park lands.

Early colonial Adelaide was shaped by the diversity and wealth of its free settlers, in contrast to the convict history of other Australian cities.