Despite being the sixth largest producer of oil in the world, and selling about two million barrels of oil per day, there is very little to show for it in terms of development.

The majority of Nigerians still live below the poverty line and infrastructural development has almost disappeared.

So whoever becomes the next president of Nigeria will face huge challenges on a number of fronts.

Who are the main presidential candidates?

Of the 20 candidates, only four are seen as having any chance of winning.

President Goodluck Jonathan of the ruling People's Democratic Party is thought to be the favourite. He became president in May 2010 after the death of his predecessor, Umaru Musa Yar'Adua.

Former military ruler Muhammadu Buhari of the Congress for Progressive Change contested both the 2003 and 2007 elections. He lost to the PDP candidate in elections that were heavily criticised by the international community.

Nuhu Ribadu, the former head of the Economic and Financial Crimes Commission, is contesting for the Action Congress of Nigeria, the largest opposition party in the country.

The fourth main candidate is Ibrahim Shekarau of the All Nigeria Peoples Party, the current governor of Kano State.

Does the opposition have any chance?

Mr Buhari will be President Jonathan's strongest challenger.

The PDP has an edge because they control two-thirds of the states and both houses of the National Assembly, in addition to the security services and state-owned media.

However, these advantages could be undone by the country's north-south divisions.

The PDP has a tradition of alternating power between the mainly Muslim north and the Christian and animist south after two terms in office. This was broken when Mr Jonathan, a southerner, succeeded Mr Yar'Adua and some PDP powerbrokers wanted their candidate in this election to be a northerner.

Mr Buhari has wide support in the north and could benefit if such feelings are widespread among ordinary people as well as the political classes.

There have been talks between the CPC and ACN to produce a joint, northern, candidate.

Although the talks have not reached a deal, such an alliance could provide a real challenge to the PDP, which has won every national election since the end of military rule in 1999.

If no candidate wins more than 50% of the vote, there will be a run-off. If this happens, the opposition may actually unite and could actually win.

But Mr Jonathan is the man to beat.