Confusion around when the coronavirus lockdown officially kicks off was rife as South Africans grappled with the semantics of President Cyril Ramaphosa's words: "...midnight on Thursday". On Monday night, Ramaphosa announced that - amid the novel coronavirus pandemic - a 21-day national lockdown would be in place from "midnight on Thursday, 26 March until midnight on Thursday, 16 April". LIVE | South Africa prepares for nationwide coronavirus lockdown - what you need to knowThis comes as countries all over the world battle to curb the spread of the virus, which causes Covid-19. By Monday, there were 402 positive cases in South Africa and Ramaphosa said the number would continue to rise. Worldwide, more than 380 000 people have been infected and more than 16 500 people have died. After Ramaphosa's announcement, many South Africans took to social media to speculate on when exactly the local lockdown would begin. They claimed the words "midnight on Thursday" were ambiguous and could mean midnight at the beginning of Thursday or midnight at the end of Thursday. But Presidency spokesperson Khusela Diko cleared up the confusion."The lockdown will begin at 23:59 on Thursday evening. Therefore, day one of the lockdown will be Friday," Diko told News24 on Tuesday. I'm tired of pretending like I know what is Thursday midnight.Is it the start of Thursday 00:00 or end of Thursday 23:59? ??— Malum Sizwe ???? (@LordSizwe) March 24, 2020 Guys! When exactly are we shutting down? It seems we’re all confused. The president said THURSDAY MIDNIGHT, 26 MARCH. That should mean when we wake up on Thursday, we’ll officially be on lockdown. Right?— Pamela Mtanga (@pamela_mtanga) March 24, 2020Why a lockdown?In his address to the nation on Monday night, Ramaphosa said sacrifices and swift action now will save lives later,"Without decisive action, the number of people infected will rapidly increase from a few hundred to tens of thousands, and within a few weeks, to hundreds of thousands," he said."While this measure will have a considerable impact on people's livelihoods, on the life of our society and on our economy, the human cost of delaying this action would be far, far greater."What will I able to do under a lockdown #COVID19 pic.twitter.com/THSRbHcD96— Dr Zweli Mkhize (@DrZweliMkhize) March 23, 2020Who will be affected?The lockdown will affect everyone.No one will be allowed to leave home for the 21 days unless under strictly controlled circumstances, which include seeking medical care, buying food, medicine or other supplies, and collecting social grants. For homeless people, shelters which meet hygiene standards are being identified, and for those who are unable to self-isolate at home, quarantine sites will be identified.READ | Coronavirus national lockdown 101: What you need to knowThe government's inter-ministerial committee is expected to hold a press briefing on Tuesday afternoon, where it's expected that several ministers in Ramaphosa's Cabinet will explain the implications and details of the lockdown. Stay up to date and stay healthy. Subscribe to Health24's Daily Dose newsletter for important updates on the spread of the coronavirus. Register and manage your newsletters in the new News24 app by clicking on the Profile tab.