The Iranian Revolution (Persian: , romanized: Enqelb-e Irn, pronounced [eelbe in]), also known as the Islamic Revolution (Persian: , romanized: Enqelb-e Eslm) was a series of events that culminated in the overthrow of the Pahlavi dynasty under Shah Mohammad Reza Pahlavi, and the replacement of his government with an Islamic republic under the rule of Ayatollah Ruhollah Khomeini, a leader of one of the factions in the revolt. The revolution was supported by various leftist and Islamist organizations.After the 1953 Iranian coup d'tat, Pahlavi had aligned with the United States and the Western Bloc to rule more firmly as an authoritarian monarch. He relied heavily on support from the United States to hold on to power which he held for a further 26 years. This led to the 1963 White Revolution and the arrest and exile of Ayatollah Khomeini in 1964. Amidst massive tensions between Khomeini and the Shah, demonstrations began in October 1977, developing into a campaign of civil resistance that included both secular and religious elements. The protests rapidly intensified in 1978 as a result of the burning of Rex Cinema which was seen as the trigger of the revolution, and between August and December that year, strikes and demonstrations paralyzed the country.

On 16 January 1979, the Shah had left Iran for exile as the last Persian monarch, leaving his duties to a regency council and Shapour Bakhtiar, who was an opposition-based prime minister. Ayatollah Khomeini was invited back to Iran by the government, and returned to Tehran to a greeting by several thousand Iranians. The royal reign collapsed shortly after, on 11 February, when guerrillas and rebel troops overwhelmed troops loyal to the Shah in armed street fighting, bringing Khomeini to official power. Iran voted by national referendum to become an Islamic republic on 1 April 1979 and to formulate and approve a new theocratic-republican constitution whereby Khomeini became supreme leader of the country in December 1979.

The revolution was unusual for the surprise it created throughout the world. It lacked many of the customary causes of revolution (defeat in war, a financial crisis, peasant rebellion, or disgruntled military); occurred in a nation that was experiencing relative prosperity; produced profound change at great speed; was massively popular; resulted in the exile of many Iranians; and replaced a pro-Western secular authoritarian monarchy with an anti-Western theocracy based on the concept of velayat-e faqih (or Guardianship of the Islamic Jurists) straddling between authoritarianism and totalitarianism. In addition to these, the revolution sought a region-wide Shia revival, and an uprooting of the existent dominant Arab Sunni hegemony in the Middle East.

The flag of Iran (Persian: پرچم ایران, romanized: parčam-è Irân, pronounced [pʰæɾˌtʃʰæme ʔiːˈɾɒːn]), also known as the Three-Coloured Flag (پرچم سه‌رنگ ایران parčam-è se rang-è Irân [pʰæɾˌtʃʰæme se ræŋ ʔiːˈɾɒːn]), is a tricolour comprising equal horizontal bands of green, white and red with the national emblem ("Allah") in red centred on the white band and the takbir written 11 times each in the Kufic script in white, at the bottom of the green and the top of the red band.This flag was adopted on 29 July 1980, as a reflection of the changes brought about by the Iranian Revolution of 1979, which resulted in the replacement of Pahlavi monarchy with an Islamic Republic, supported by a wide range of Islamist organizations and student movements. In opposition to the current regime in Iran, a number of Iranian exiles (particularly in Los Angeles, Paris, London, Berlin, Amsterdam, etc.) continue to use the Iranian tricolor with the Lion and Sun at the center.