Muhammadu Buhari, leader of Nigeria's APC party, has become the first opposition candidate to win a presidential election in the country.Goodluck Jonathan, leader of the People's Democratic Party (PDP), and president since 2010, has conceded defeat following confirmation that General Buhari – a former military leader who came to power after a coup in 1983 – had beaten him by more than 2.5 million votes.This year's election featured biometric voters' cards, which have been introduced to avoid the allegations of vote rigging that which have plagued previous ballots.During the election, voters had to validate their cards using a fingerprint reader. Technical problems with some readers caused delays, with some voters – including Goodluck Jonathan – reportedly having to try to register for many minutes before resorting to manual verification.INEC, Nigeria's electoral commission, faced criticism for introducing the biometric voting system without testing it on a smaller electoral process. However, Dr Bakili Muluzi, former President of Malawi and chairperson of the Commonwealth Observer Group, said in an interim statement on the elections: "Notwithstanding some challenges, the introduction of biometric Permanent Voter Cards is, in our view, a major factor in enhancing the integrity of the electoral process, by ensuring that only eligible voters could cast ballots on polling day."This election is a milestone for Africa's biggest economy. Although there have been allegations of fraud and problems with using biometric voting technology, observers praised the election, saying that the whole process pointed to greater democratisation in the country.Santiago Fisas, head of the EU observer mission, told reporters: "The EU observation mission strongly encourages INEC efforts in difficult circumstances, and in spite of strong tension and criticism, to maintain the highest level of impartiality."