Iran elects a new president on 12 June amid mounting pressure for reform from within and outside the country.
Iran possesses nearly a 10th of the world's oil, yet fuel is rationed. Inflation is at unprecedented levels, and there is disenchantment with government spending policies which are largely seen as populist and which the country cannot afford.
Read more on the current state of the country in facts and figures.
Iran comprises a mix of ethnic and religious groups, but is led by Shia Muslim clerics.
A president is publicly elected every four years from a candidate list vetted by the influential Guardian Council, half of whose members are themselves appointed by the powerful and conservative Supreme Leader, Ayatollah Ali Khameni.
Iran's population doubled between 1975 and 2000, and an increasingly large proportion of it is young.
About half its 71m people are under 25; nearly two-thirds under 30. This youthful population is clearly demonstrated in the graph below.
Literacy rates among young people bear comparison with much of the world, although there is a marked difference between men (87.3%) and women (77.2%) over the age of 24.
Iran's health indicators are among the best in the Middle East because of a government drive over the last 20 years to improve the nation's health by focussing on primary care and disease prevention in both rural and urban areas.
The government has invested heavily in health care
In 2005 Iran spent 7.8% of its GDP on health, compared with neighbours Saudi Arabia's figure of 3.4% (2007), Iraq's 4.1% (2007) and Turkmenistan's 4.8% (2005). The UK spent 8.2% of GDP on health care in 2005.
But massive unemployment - analysts put it between 20% and 30% - has led to a "brain drain" from the country, leaving it short of (among others) health professionals, particularly doctors and dentists.
Yet life expectancy is above the global average (though nowhere near that of most of the Western world), diabetes and tuberculosis are at relatively low levels.
Only 4% of its population was undernourished in 2003, according to the World Bank, though 4.3% of under-fives were overweight - putting it a lot higher up the global "league table" of child obesity.
Iran has one of the strongest-performing economies of the major oil-producing countries in the Middle East.
But critics argue it has squandered much of this wealth through imprudent public-sector spending, subsidies, corruption and inefficiency.
Major trading partners:
EU (24.3% of total import/exports), China (14.3%), Japan (9.8%), South Korea (6.3%), Turkey (5.6%)
Economically active population: 23.5 million (2006 estimate, CBI)
GDP: 294.1 billion dollars, (2007 US estimate)
Unemployment: 9.6%, rising to 20.3% among people under 24 (spring 2008, CBI)
Annual inflation: 25.3% (May 2009, CBI)
Oil production: 4.4m barrels per day (2006, IMF)
An International Monetary Fund report estimated that the country's non-oil fiscal deficit would rise to about 18% of its GDP by the end of the last financial year, making it even more at risk to a fall in oil prices.
While UN sanctions, imposed over its refusal to suspend its uranium enrichment programme have played some role in Iran's recent economic decline, the general feeling is that although they have made some aspects of business more difficult, they are not economically that significant.
Financial institutions and assets were targeted, deterring foreign banks from doing business in Tehran.
Petrol rationing, introduced in June 2007, sparked angry protests in which a number of petrol stations were burnt to the ground.
As the world's fourth-highest oil and gas producer, Iran enjoys good economic growth, but commentators fear it is too reliant on its petrorchemical revenues.
IRAN'S GAS IMPORTS/EXPORTS
Proven reserves 2007 - 27.80 trillion cubic m (15.7% of world total)
Production - 111.9bn cu m (3.8%)
Consumption - 111.8bn cu m (3.8%)
Source: BP 2008 report
They account for 80% of its export earnings, yet a lack of domestic refining capacity means it imports around 40% of its petrol.
Much of its oil income is used to fund public spending and subsidies.
The IMF estimates that energy subsidies amount to about 17.5% of its gross domestic product in a country that has some of the cheapest petrol in the world - and fuel rationing.
And while the country boasts the biggest reserves of natural gas in the Middle East (and second only to Russia globally), its consumption is also markedly high, behind only the US and Russia.