South Africa held a national election Wednesday that could be the country’s most hotly contested in 30 years, with the long-ruling African National Congress party facing a stern test to hold onto its majority.

The ANC has been the majority party and in government ever since the end of South Africa’s apartheid system of white minority rule and the establishment of democracy in 1994 and has held the presidency since then.

Under the South African political system, people vote for parties and not directly for the President in their national elections. The two processes are separate, even though they are linked: Voters choose parties to decide the makeup of Parliament and lawmakers then elect the President.

Here’s a guide to the main election in Africa’s most advanced country and why it might be complicated this time for Parliament to choose the President.

The election took place on just one day, with polls opening at 7 a.m. and closing at 9 p.m. across the country of 62 million people, which has nine provinces. Nearly 28 million South Africans were registered to vote to decide the makeup of their national as well as provincial legislatures.

South Africans can choose parties, or for the first time independent candidates, to go to Parliament. Parties get seats in Parliament according to their share of the vote.

Counting starts immediately after the polls close and the final results are expected by Sunday, according to the independent electoral commission that runs the election.