The ANC, which led the fight against apartheid, has governed the country since 1994.
Challenging the party are the centrist Democratic Alliance (DA) and the far-left Economic Freedom Fighters (EFF), which has won 8%, based on the official early results. Why has the ANC lost support? Young people queuing to vote spoke of their difficulties in finding jobs, with unemployment at 27%.
One young voter said her future employment prospects were on her mind.