Iran is a paradox like no other country in the Middle East.
On the one had an overwhelmingly young, dynamic and constantly changing country but whose politics is set within the unchanging principles and guidelines of the Islamic Republic.
A hugely diverse country with millions of highly successful entrepreneurs and graduate students living and working in the United States - many of them with US passports, but which is also one of the most internationally isolated countries with sanctions still imposed by Washington.
These and the hundreds of other fascinating anomalies about this country of 80 million people reach their pinnacle in what is perhaps the greatest paradox about Iran.
It is a country which much of the world sees as an undemocratic country governed by a stern theocracy - and yet elections in Iran offer profoundly different political visions and ideas to a highly engaged electorate.
These elections also reflect profound differences within the country.
There is no doubt that the Islamic Republic’s political system operates within a clear ideological framework in which the legitimacy of the theocracy of Islamic Revolution is paramount - and any threat to it is not tolerated.
Yet this Friday’s presidential poll offers a genuinely stark political choice to Iranian voters and who they choose will have profound consequences in Iran and across the world.
After his government reached the landmark nuclear deal with global powers in 2015 - a deal in which the international community promised to lift a series of wide-ranging economic sanctions in return for Iran ending its nuclear programme and agreeing to a strict inspections programme, President Hassan Rouhani is facing a fight for his political life.
The lifting of those sanctions has been slow, and the huge majority who swept him to power in 2013, and who believed that life would be better for them after the nuclear deal, feel let down and disillusioned.
His campaign has promised to maintain Iran’s links with the outside world which he argues is the only way to complete the lifting of sanctions. His success or failure will determine the success or failure of the entire Reformist movement in Iran that wants to see greater co-operation with the West.
Against him is Ebrahim Raisi, a man whose political history, ideas and vision for Iran could not be more different from Rouhani’s. A clerical judge, he is known for being part of a Sharia court which in 1988 sentenced hundreds of dissidents to death.
Until now Mr Raisi has not held any prominent political office or elected position.
However, like in so many other parts of the world, he offers a seductive populist message of economic self-reliance and a withdrawal from dependence on global links.
He has lacerated the achievements of the Reformists saying the nuclear deal (which he is outwardly committed to) has been a failure for ordinary people.
He preaches a thinly detailed yet highly popular message of Iran relying on its economic strengths - especially of its oil and gas reserves - saying he will create a million jobs a year.
To a hugely young population where unemployment officially runs at nearly 25% and where an expensive and high quality university degree does not guarantee a career - that is a powerful message.
It’s also a powerful message in a society where an extremely wealth elite which drives luxury western sports cars are perceived as being the only ones to have benefited from greater links with the outside world.
The international implications of a Raisi victory and a Rouhani loss are huge.
It’ll mean that Iran will be led by a President who comes from an ideology which is instinctively suspicious of the West and would not shrink from confronting it in the region. Given that Iran is a critical power in Syria, Iraq and Yemen - three key conflicts in the Middle East - that would clearly affect Western interests.
Rouhani’s best hope is for a high turnout. If the largely apathetic urban voters of Iran stay away - the more conservative provincial and rural vote will carry Raisi to power.
His other key hope reflects another paradox of Iranian life; in a region in which women don’t play a decisive role in political life, Rouhani will need as many young Iranian women to turn out to vote for him in order to lead an Islamic Republic.