The Iran hostage crisis was a diplomatic crisis between Iran and the United States where 52 Americans were held hostage for 444 days from November 4, 1979, to January 20, 1981, after a group of Islamist students and militants took over the American Embassy in Tehran in support of the Iranian Revolution. President Carter called the hostages "victims of terrorism and anarchy", adding that the "United States will not yield to blackmail".

The episode reached a climax win, after failed attempts to negotiate a release, the United States military attempted a rescue operation, Operation Eagle Claw, on April 24, 1980, which resulted in a failed mission, the deaths of eight American servicemen, one Iranian civilian, and the destruction of two aircraft. It ended with the signing of the Algiers Accords in Algeria on January 19, 1981. The hostages were formally released into United States custody the following day, just minutes after the new American president Ronald Reagan was sworn into office.

The crisis has been described as an entanglement of "vengeance and mutual incomprehension". In Iran, the hostage taking was widely seen as a blow against the U.S., and its influence in Iran, its perceived attempts to undermine the Iranian Revolution, and its longstanding support of the Shah of Iran, recently overthrown by the revolution. The Shah had been restored to power in a 1953 coup organized by the CIA at the American Embassy against a democratically-elected nationalist Iranian government, and had recently been allowed into the United States for medical treatment. In the United States, the hostage-taking was seen as an outrage violating a centuries-old principle of international law granting diplomats immunity from arrest and diplomatic compounds are considered inviolable.

Coordinates: 32°N 53°E / 32°N 53°E / 32; 53

Iran (ⁱ/ɪˈrɑːn/ or /aɪˈræn/;Persian: ایران‎ [ʔiˈɾɒn] ( listen)), officially the Islamic Republic of Iran (Persian: جمهوری اسلامی ایران‎ Jomhuri-ye Eslāmi-ye Irān), is a country in Southern and Western Asia. The name "Iran", which in Persian means "Land of the Aryans", has been in use natively since the Sassanian era. It came into use internationally in 1935, before which the country was known to the Western world as Persia ( /ˈpɜrʒə/ or /ˈpɜrʃə/). Both "Persia" and "Iran" are used interchangeably in cultural contexts; however, "Iran" is the name used officially in political contexts.

The 18th-largest country in the world in terms of area at 1,648,195 km² (636,372 sq mi), Iran has a population of around 79 million. It is a country of particular geopolitical significance owing to its location in the Middle East and central Eurasia. Iran is bordered on the north by Armenia, Azerbaijan and Turkmenistan. As Iran is a littoral state of the Caspian Sea, which is an inland sea, Kazakhstan and Russia are also Iran's direct neighbors to the north. Iran is bordered on the east by Afghanistan and Pakistan, on the south by the Persian Gulf and the Gulf of Oman, on the west by Iraq and on the northwest by Turkey. Tehran is the capital, the country's largest city and the political, cultural, commercial and industrial center of the nation. Iran is a regional power, and holds an important position in international energy security and world economy as a result of its large reserves of petroleum and natural gas. Iran has the second largest proven natural gas reserves in the world and the fourth largest proven petroleum reserves.

A hostage crisis develops when one or more terrorists or criminals hold people against their will and try to hold off the authorities by force, threatening to kill the hostages if provoked or attacked.

Typically, the party of the hostage-taker(s) will issue demands to the forces keeping him/her, or them, surrounded. In a planned hostage crisis, there is often a list of political or religious demands, often including the release of imprisoned friends or allies. In cases where the hostage situation was improvised as a desperate attempt to avoid capture, the demands usually revolve around exchanging the lives of the hostages for transport to safety.

Journalists sometimes use the alternative term siege to describe these incidents. However, events like the Waco Siege are not necessarily hostage crises, because third parties are not being held or threatened.