Here are some high points of the elections:
Timings: Polls opened at 8.00 am local time and will close at 5 pm. The timing in Karachi was extended owing to disruptions in the voting procedure.
Registered voters: 86,189,802
Candidates: 5,000 for 342-seat National Assembly. Of these, 272 are directly elected.
Provincial Assembly candidates: 11,692
Maximum no. of candidates for 1 seat: NA-48 constituency in Islamabad, where 51 candidates are contesting.
Security personnel: Over 6,00,000.
Polling stations: More than 73,000 (of these, 20,000 are risk-prone)
Main contenders: Bilawal Bhutto (PPP), Nawaz Sharif (PML-N), Imran Khan (PTI).