Presidential election is being held today to elect the 14th President of Pakistan for next five years.Asif Ali Zardari, the joint candidate of PPP and the PML-N, and Sunni Ittehad Council's candidate Mahmood Khan Achakzai are vying for the office of President.The President is elected by an electoral college comprising members of the Senate, National Assembly and the four provincial assemblies.Voting is held through a secret ballot.A joint session of the parliament will be held at the parliament house in Islamabad today in which the members of National Assembly and the Senate will exercise their right to vote.Similarly, the provincial assemblies will also hold their sessions today for the election.Polling will begin at ten am and continue till 4:00 p.m.Source: Radio Pakistan