Iran elects a new parliament on 14 March 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.
Read more on the current state of the country, on the eve of the parliamentary elections, in facts and figures:
Iran comprises a mix of ethnic and religious groups, but is led by clerics of the predominant Shia Muslims.
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.
A parliament is elected every four years, but its legislation is also vetted to ensure compliance with Islamic law.
A brief period of a liberal presidency failed to satisfy an electorate keen for more openness and freedom, not least because many of President Mohammad Khatami's policies were thwarted or watered down by the hardline establishment.
Now dissatisfaction is widespread after another conservative, Mahmoud Ahmadinejad, became president.
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.
Literacy among young males bears comparison with much of the world, although the figure in 2002, the date of the last World Bank international comparison, showed the proportion of young females still lagging behind.
Adult literacy rates are less encouraging.
Iran's massive unemployment problem - 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, and notably few people smoke.
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.
In 2003 Iran spent 6.5% of its GDP on health, just under half of that on public health.
IRAN'S TRADING PARTNERS
% of total imports/exports 2006
EU - 27.8
China - 12.3
Japan - 9.8
S Korea - 6.1
Turkey - 5.5
UAE - 4.4
Other - 34.1
Source: European Commission
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.
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.
IRAN'S GAS IMPORTS AND EXPORTS
Proven reserves - 28.1 trillion cubic m (15.5% of world total)
Production - 105bn cu m (3.7%)
Consumption - 105.1bn cu m (3.7%)
Source: BP 2007
As the world's fourth-highest oil and gas producer, Iran enjoys good economic growth, but commentators fear it is too reliant on its oil revenues.
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.