The International Atomic Energy Agency is an independent watchdog at the center of negotiations with Iran and its pursuit of a nuclear weapons program.
Established in 1957, the IAEA promotes safe and peaceful uses of nuclear energy and serves as the world's nuclear weapons inspector. It reports to the United Nations and, when necessary, to the Security Council.
The agency will play a major role in verifying the terms of an agreement reached Saturday between Iran and six leading world powers to cap Iran's nuclear program in exchange for ending economic sanctions.
IAEA inspectors regularly visit Iran's declared nuclear facilities, but the agreement could pave the way for further inspections of guarded facilities.
Inspectors were twice allowed entry in 2005 onto Iran's Parchin military base, believed to be the site of Iran's secret nuclear activity, but were only allowed to examine limited buildings in the facility.
The IAEA intends to continue to press for a full inspection of the Parchin military base, which Iranian officials have been willing to discuss further. However, they want restrictions on what the agency can disclose publicly about operations at the facility.
The agreement allows for inspections of a nuclear facility in the city of Arak among others, and the agency will also be responsible for monitoring Iran's compliance of the international agreement that calls on Iran to stop production of nuclear fuel that could become weapons grade.
IAEA Director General Yukiya Amano has been in frequent talks with Iranian officials, including a November meeting in Tehran at the invitation of Ali Akbar Salehi, the head of Iran's atomic energy organization. Amano called the agreement an important first step, according to Reuters.
The United States is one of the IAEA's biggest backers, contributing millions of dollars annually to help fund the agency's programs. There are more than 100 member nations to the IAEA, which is funded by annual dues and other voluntary contributions.