term, with cricket star Imran Khan a wildcard contender for power after years in the political wilderness.
The outgoing Pakistan People's Party has conducted a low-key campaign and many analysts expect it to perform badly after a chequered record in power for the past five years.
Here are key facts about Pakistan:
GEOGRAPHY: Located in South Asia, Pakistan borders Iran to the west, India to the east, Afghanistan to the northwest, China to the north and lies on the Arabian Sea.
AREA: Total area is 796,096 square kilometres (307,374 square miles).
POPULATION: Around 180 million.
LANGUAGE: Urdu is the national language, English is the official language used in business dealings, government contracts, court and legal proceedings.
RELIGION: The state religion is Islam and 97% of the population is Muslim. There is a three% minority of Hindus, Buddhists, Christians, Sikhs and other communities.
LITERACY RATE: The official literacy rate is 55%, 65% for men and 35% among women.
SYSTEM OF GOVERNMENT: Constitutional Islamic republic and parliamentary democracy. An electoral college comprising the federal parliament and four provincial assemblies elect a president who is also technically supreme commander of the armed forces. Asif Ali Zardari, elected on September 9, 2008, is the country's 11th president.
NATIONAL DAY: August 14, when Pakistan was created in 1947 after India's partition.
CURRENCY: The monetary unit is the rupee which consists of 100 paisa. Its value has crumbled in recent years and the current exchange rate is around 98 to the dollar.
NATIONAL FLAG: The flag is two thirds green, and one third white, with a white crescent and five-pointed star in the middle.
DEFENCE: Pakistan has more than half a million in the armed forces. The country became an atomic power in May 1998 when it conducted six nuclear tests.
ECONOMY: The economy has suffered from Taliban and Al-Qaeda-linked violence and crippling power shortages. Major produce includes cotton, wheat, rice and sugarcane.
EXPORT: Textiles, rice, leather, sports goods and carpets.
IMPORTS: Oil, petroleum products and machinery.
GROSS DOMESTIC PRODUCT: $210.2 billion in 2011, according to the World Bank, $1,120 per capita. GDP growth in 2011 was 3.0%.
UNEMPLOYMENT RATE: 8%.
POPULATION GROWTH: 2.2%.
POVERTY: The government estimates that 22% of the population live in poverty but independent economists put the figure closer to 30%.