The nuclear agreement between Iran and six world powers is the result of more than a decade of diplomacy designed to ensure the Islamic Republic cannot develop nuclear weapons.
The challenge of the negotiations has in no small part been made more difficult by the fact that the U.S. and Iran have had no formal, direct diplomatic relations since the 1979 Iranian Revolution that deposed the Western-friendly shah.
Iran's nuclear program first garnered serious attention in 2002. The fear that they would develop nuclear weapons, bringing a whole new arms race to the already-volatile Mideast, immediately brought international negotiators to Tehran.
Eventually, the U.S., along with France, Britain, Germany, Russia, and China, would produce an accord with Iran, but not before lots of starts and stops along the way.
The following is a timeline of how they reached an agreement.