What is at stake in Zambia's elections?
Zambia is heading for the polls just 18 months after the last presidential election, which saw Edgar Lungu win by less than 28,000 votes. BBC Focus on Africa editor Rachael Akidi looks at the issues in this election.
What is special about this election?
Zambia has been hailed as one of Africa's most stable and mature democracies. It has held regular multi-party elections since 1991, including in 2011 when President Rupiah Banda lost, accepted defeat and stepped down.
But this poll is being contested under new rules.
The constitution was amended in response to the deaths of two sitting presidents in less than five years, which meant early elections on both occasions.
Under the new rules, a presidential candidate is required to have a running mate who will become vice-president and take over if the president dies in office.
For the first time, the winner must also secure a minimum of one vote more than 50% of the ballots cast. Otherwise the poll will go into a second round, to be held within 37 days.
This means the president should have gained the support of a wider cross-section of society.
In addition to the election, the people will also be voting in a constitutional referendum on the same day, to decide whether to amend the bill of rights.
This gives all Zambians the right to food, shelter, employment and healthcare.
It also bans homosexual acts, abortion and raises the age of consent to 19.
Some civil society groups have criticised the decision to hold a referendum question in parallel to the general election.
They say amending the bill of rights in the constitution is a matter of such gravity that it should be addressed on its own merits, without subconscious influence from the positions taken by political leaders.
Who are the main candidates?
There are nine presidential candidates, with President Edgar Lungu, 59, of the ruling Patriotic Front (PF) and Hakainde Hichelema of the United Party for National Development (UPND), 54, the front-runners.
Both men stood in last year's election, which Mr Lungu narrowly won.
Before becoming president, Mr Lungu, a lawyer, served in Mr Sata's government as minister for justice and defence. He also held several leadership positions within his party.
This election will in many ways be a personal referendum on him. He has to convince the voters why they should extend his mandate, given the challenges the country is grappling with.
Mr Lungu enjoys support mainly in his home area of Eastern province, the capital, Lusaka, and the Copperbelt plus the Bemba-speaking regions of the country.
Mr Hichilema is a wealthy businessman, who has contested nearly all elections in Zambia since 2006. He enjoys overwhelming support in Southern Province, his home region.
Mr Hichilema is a highly educated economist and has a solid track record in the private sector. He has promised to bring the same sound economic management to the country if elected.
He is commonly referred to by his initials, HH. His youthful looks and articulate speech attract young voters.
The other contenders include Edith Nawakwi, a veteran politician standing for the Forum for Democracy and Development (FDD).
The only female candidate in the race, she came third in last year's by-election with only 0.9% of the vote.
Also standing is former Justice Minister Wynter Kabimba. A former secretary general of the PF, he was for many years touted as a possible successor to late Mr Sata, before his impetuous dismissal from both posts. He is running for the Rainbow Party.
What are the issues?
The key issues are youth unemployment, poverty, education and healthcare. But the dominant theme linking all these will be the economy.
Only a couple of years ago, Zambia was hailed as one of Africa's fastest-growing economies.
The price of copper, its main export, was at an all-time high. The country was a destination of choice for foreign direct investment - especially from China.
With the global fall in commodity prices, the economy of Africa's second largest copper producer has been struggling.
Several mines have been forced to close, resulting in massive unemployment for thousands of people.
In addition, the country has also been facing a drought and an acute power shortage, which is having a huge impact on economic productivity.
The currency, the kwacha, is slowly recovering after it fell sharply over the last 18 months. At one time, it was one of the world's worst performing currencies.
Last year, the president was criticised when he turned to divine intervention, asking the country to pray for the kwacha.
The government is now seeking an International Monetary Fund bailout due to its rising debt.
The cost of living for many Zambians is at an all-time high.
According to the June report of the Jesuit Centre for Theological Reflection, a local think tank, a family of six needs around $481 a month to afford the most basic needs in Lusaka. This is four times the average monthly income in the country.
The opposition UPND accuses President Lungu of presiding over the "collapse" of the economy.
The party's director for policy Cholwe Beyani says: "The economy is on death row... the exchequer is bankrupt and the government can't even pay public service workers at the moment".
The opposition blames the country's economic problems on both poor economic policies and a lack of fiscal discipline by the government.
The ruling party insists the economy is not in crisis. PF spokesperson Frank Bwalya says: "The starting point for us is not that the economy is not doing well, but what can be done to make it better".
He says the party has a plan to diversify the economy. "We want to move away from the mono-economy and stop our dependence on copper as our main foreign-exchange earner."
Analysts say both sides have not properly articulated solutions to the economic crisis during the campaigns.
Whoever wins the election will have the huge task of reviving Zambia's economic fortunes.
Will there be any violence?
It looks as though it will be yet another tight race and passions will be running high.
There was not violence after last year's presidential by-election, triggered by the death of President Michael Sata, although Mr Hichilema narrowly lost and claimed there was rigging.
However, the run-up to Thursday's poll has been marred by clashes between rival supporters.
The Electoral Commission of Zambia (ECZ) was forced to suspend campaigning in Lusaka for 10 days because of the violence.
In June, the Zambian police fired tear gas to disperse staff protesting against the closure of leading daily newspaper, The Post.
The independent newspaper was shut down by the authorities over an unpaid tax bill of $6.1m (£4.1m).
The newspaper and some local human rights groups condemned the move, with the paper's editor saying it was a politically motivated attempt to clamp down on the independent press ahead of the elections.