Iran, officially the Islamic Republic of Iran and formerly known internationally as Persia until 1935, is a country in Central Eurasia. It is located on the northeastern shore of the Persian Gulf and the southern shore of the Caspian Sea. Both "Persia" and "Iran" are used interchangeably in cultural context, however, Iran is the name used officially in political context. The name Iran is a derivative of Aryan, and means "Land of the Aryans".

The 18th largest country in the world in terms of area at 1,648,195 km, Iran has a population of over seventy million. It is a country of special geostrategic and geopolitical significance due to its location, size and vast reserves of oil and natural gas.

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 with ambitions of being the area's superpower.

Iran is home to one of the world's oldest continuous major civilizations, with historical and urban settlements dating back to 7000 BC. The first Iranian dynasty formed during the Elamite kingdom in 2800 BC. The Iranian Medes unified Iran into an empire in 625 BC. They were succeeded by three Iranian Empires, the Achaemenids, Parthians and Sassanids, which governed Iran for more than 1000 years. Iranian post-Islamic dynasties and empires expanded the Persian language and culture throughout the Iranian plateau.

The blossoming of Persian literature, philosophy, medicine, astronomy, mathematics and art became major elements of Muslim civilization and started with the Samanids. Iran was once again reunified as an independent state in 1501 by the Safavid dynasty-who promoted Shi'a Islam as the official religion of their empire, marking one of the most important turning points in the history of Islam. Persia's Constitutional Revolution established the nation's first parliament-known as the Majlis-in 1906, within a constitutional monarchy. Iran officially became an Islamic Republic on April 1, 1979, following the Iranian Revolution.

U.S.-Iranian relations have been strained since a group of Iranian students seized the U.S. Embassy in Tehran on November 4, 1979 and held it until January 20, 1981. During 1980-88, Iran fought a bloody, indecisive war with Iraq that eventually expanded into the Persian Gulf and led to clashes between U.S. Navy and Iranian military forces between 1987 and 1988. Iran has been designated a state sponsor of terrorism for its activities in Lebanon and elsewhere in the world and remains subject to U.S., U.N., and EU economic sanctions and export controls because of its continued involvement in terrorism and its nuclear weapons ambitions.

(Source: Wikipedia and CIA Fact Book)