Iran became an Islamic republic in 1979, when the monarchy was overthrown and clerics assumed political control under Ayatollah Khomeini.

The revolution put an end to the rule of the Shah, who had alienated powerful religious, political and popular forces with a programme of modernisation and Westernisation, coupled with heavy repression of dissent.

Iran was one of the greatest empires of the ancient world, and has long maintained a distinct cultural identity by retaining its own language and adhering to the Shia interpretation of Islam.

• Read more country profiles - Profiles by BBC Monitoring

LEADERS

Supreme Leader: Ayatollah Ali Khamenei

The Supreme Leader - the highest power in the land - appoints the heads of the judiciary, military and media. He also confirms the election of the president.

Ali Khamenei was appointed for life in June 1989, succeeding Ayatollah Khomeini. He previously served two consecutive terms as president in the 1980s.

President-elect: Masoud Pezeshkian

Reformist Masoud Pezeshkian was elected as Iran president in July 2024, beating his hardline conservative rival Saeed Jalili.

He won 53.3% of the more than 30 million votes while Mr Jalili polled at 44.3% in the second round run-off.

The run-off came after no candidate secured a majority in the first round of the election, which saw a historically low voter turnout of 40%.

The election was called after Iran's previous president Ebrahim Raisi was killed in a helicopter crash in May, in which seven others also died.

Dr Pezeshkian, a heart surgeon and member of the Iranian parliament, has been critical of Iran's notorious morality police and caused a stir after promising "unity and cohesion", as well as an end to Iran's "isolation" from the world.

He has also called for "constructive negotiations" with Western powers over a renewal of the faltering 2015 nuclear deal in which Iran agreed to curb its nuclear programme in return for an easing of Western sanctions.

The president is the top elected official and second in rank to the supreme leader. He is responsible for the day-to-day running of the government and has significant influence over domestic policy and foreign affairs.

However, his powers are relatively limited - especially in security matters. The president's interior ministry runs the national police force. However, its commander was appointed by the supreme leader and is answerable directly to him.

The same is true of the commander of the Islamic Revolutionary Guard Corps and the Basij.

The president's powers can also be checked by parliament, which introduces new laws.

In turn, the Guardian Council - which contains close allies of the supreme leader - has the job of approving new laws and can veto them.

MEDIA

All broadcasting from Iranian soil is controlled by the state and reflects official ideology. A wider range of opinion may be found online and in the printed press.

Iran is one of the world's most repressive countries for journalists, says Reporters Without Borders.

• Read full media profile

TIMELINE

Some key dates in Iran's recent history:

1794 - Mohammad Khan Qajar seizes power and founds the Qajar dynasty.

1921 - Military commander Reza Khan seizes power and is later crowned Reza Shah Pahlavi.

1941 - Britain and Russia occupy Iran during World War Two.

1953 - Coup engineered by British and US intelligence services overthrows Prime Minister Mohammad Mosaddegh.

1979 - Iranian revolution unseats the Shah.

1980-1988 - Iran-Iraq war.

1989 - Ayatollah Khomeini, the supreme leader and founder of the Islamic Republic, dies and is replaced by Ayatollah Ali Khamenei.

1997 - Reformist Mohammad Khatami is elected president in a landslide.

2004 - US says Iran's nuclear programme is a growing threat and calls for international sanctions.

2005 - Hardline Mahmoud Ahmadinejad is elected president.

2009 - Ahmadinejad is re-elected in a disputed election triggering months of mass protests known as the "Green Movement".

2013 - Moderate Hassan Rouhani elected president.

2015 - Iran and major world powers reach agreement over its controversial nuclear activities. Tehran agrees to cut its nuclear programme in return for partial lifting of sanctions.

2018 - US withdraws from the 2015 international deal on Iran's nuclear programme and imposes sanctions on Tehran.

2020 - Qasem Soleimani, head of IRGC's external arm known as the Quds Force and arguably the most powerful figure in Iran after Ayatollah Khamenei, is assassinated by the US in Iraq.

2021 - Hardline Ebrahim Raisi is elected as president.

2022 - Mass nationwide protests after the death in police custody of Mahsa Amini.

2024 - President Raisi is killed in a helicopter crash, reformist Masoud Pezeshkian is subsequently elected president.