The January 9-15th 2011 Southern Sudan referendum is for the Southern Sudanese people to vote on whether they want to remain part of the larger Sudan or separate to become a new independent country.
Why is this referendum taking place?
Since Sudan's independence from its colonial powers in 1956 the country has been in an almost continual state of civil war, epitomized by a north-south divide.
In an effort to stem the violence, a series of peace keeping treaties were negotiated and signed. These cumulated into what is known as the Comprehensive Peace Agreement (CPA) signed in 2005. The outcomes of the CPA meant that the Southern Sudan was allowed to become an autonomous region with its own government. Under the CPA this region would also be allowed to carry out a referendum on whether it wished to separate from the North and become a new country.
Who will vote?
Only southerners are eligible to take part in the poll and in order to vote they had to register before the registration deadline on December 1st. It is estimated that around 4 million southerners have done this.
How will the voting happen?
Voting will start on January 9th and will lasts for seven days.
To cast a vote voters should attend a polling station between 10am and 7pm. Upon arrival voters will need to prove they are registered to vote using their registration card before they will be given their ballot paper. Using this ballot paper they will either vote for separation (a lone hand) or vote to stay with the North (two clasping hands) before putting the ballot into the sealed ballot box. After completing this process the voter's hand will be marked with indelible ink to show they have voted. All of this will be monitored by independent observers.
How will the vote be decided?
Firstly at least 60% of registered voters must take part for the referendum to be valid. Secondly there must be a majority vote to either side. All of which is explained in the Southern Sudan Referendum Act.
With low literacy levels and little history of voting, achieving the 60% requirement may be difficult to achieve. However steps have been taken to increasing the likelihood of voting by providing pictures with the words to help assist the voters.
What happens then?
After the polls close on January 15th the counting will begin at polling stations as local and international observers watch. Results will be posted at each polling site. The ballots will then be sent to Juba and verified using a double blind data entry system.
Assuming that the verdict is to secede, on July 9th 2011 Africa's newest country will come into being. This will be exactly six years after the peace deal took effect. 
Is that it?
No. There are still a number of practical points to be resolved including: exact border demarcation; the ownership of the national oil fields, which straddle both the north and south; how Sudan's current debt will be shared; in which country the contentious Abyei region will reside; and other problems.
What are the chances of any violence around the referendum?
While many worry that the unpopularity of the referendum in the north may lead to conflict, more recent opinion suggests this danger is diminishing. Both governments have stated that they will respect the outcome of the referendum whatever that is.
However there is concern that local groups and militia in certain hot spots and around potential border regions may incite violence. While these groups are likely to be lone groups unhappy with the process or future border demarcation, any violence they are involved in may provoke a wider conflict.
Also there are still a number of unresolved issues, as mentioned above, which could lead to further conflict as they are negotiated.
Full name: Republic of Sudan Population: 43.2 million Population of Southern Sudan: Estimated 7.4-9.5m (UN, 2010) Capital: Khartoum Area: 2.5 million sq km (966,757 sq miles) (10th largest country in the world) Major languages: Arabic, English (official), others Major religions: Sunni Muslim (70% mostly in the north), Christianity (5% mainly in the south), Animism and other indigenous beliefs (25%). Life expectancy: 58 years (men), 61 years (women) Infant Mortality Rate: 72.39 deaths/1,000 live births Urban population: 43% of total population (2008) GNI per capita: US $1,220 (World Bank, 2009) Population below the poverty line: 40% (2004)