After a long night of vote counting, we are expected to get the national declaration of the result at around breakfast time on Friday June 24.
Although a vote to remain would maintain the status quo, here is a look at what could happen.
A vote to stay in the EU would spark huge celebrations among everyone who campaigned to remain in the European 28-member bloc.
The value of the pound is expected to rally and economists would breathe a sigh of relief because the result would end economic uncertainty.
As an indication of things to come, stock markets and sterling surged on Monday as traders placed bets on Britain staying in the EU.
Even if Mr Cameron is victorious in the EU referendum, he could still face calls to step down unless he gets a very convincing majority.
Nevertheless a Remain win will mark an enormous defeat for Brexiteers and Mr Cameron’s rivals. Eurosceptics will have to make do with pushing for reform within the EU.
So if you decide to vote to stay in the EU, you’ll have to stop moaning about immigration because you’ve missed your chance to leave.
EU officials and member states will warmly welcome Britain’s decision to stay in the EU as an important boost for European unity.
But European Council president Donald Tusk believes that the union will still need to respond to growing Euroscepticism across the Continent.
“Whatever the UK vote is, we must take long hard look on the future of the Union. Would be foolish to ignore such a warning signal,” he posted on Twitter.
The European Parliament would next need to approve some parts of Mr Cameron’s controversial deal on Britain’s membership of the EU.
Its president Martin Schulz has guaranteed that they would immediately start to “legislate on the proposal” in the wake of the EU referendum.
But Mr Schulz said he could “not guarantee about the result”, which needs the backing of MEPs.
Mr Cameron has ruled out a second referendum saying: “If we vote to stay, we stay and that’s it.”
But Ukip leader Nigel Farage has indicated that that he would battle for a second referendum if the Remain camp wins by just a narrow margin.
He told the Mirror: ”In a 52-48 referendum this would be unfinished business by a long way. If the Remain campaign win two-thirds to one-third that ends it.”
A Remain vote would prevent calls for another referendum on Scottish independence for now because most Scots support staying the EU.
