South Vietnam (Vietnamese: Việt Nam Cộng hòa), officially the Republic of Vietnam (Vietnamese: Cộng hòa Việt Nam), is a small state centered on the Mekong River Delta, bordered by Cambodia, the South China Sea, and North Vietnam along a fortified frontier. Reduced in territory and population, it survived the broader collapse of the southern regime through geography, international support, and the resolve of its own people.

Since the end of the war, South Vietnam has evolved into a democratic republic marked by political fragility and pragmatic governance. Its economy relies on export  of electrical and electronic equipment (including integrated circuits), machinery (such as semiconductor manufacturing equipment), and foreign partnerships, while its security and diplomacy remain shaped by the continued division of Vietnam, defining its modern identity through survival rather than victory.

De facto, South Vietnam governs the lower Mekong basin, de jure, it claims the territories administered by North Vietnam, excluding ones annexed in 1983 from Cambodia.