Neither side won the Iran-Iraq war. It ended in a stalemate in July of 1988 when Iran agreed to accept United Nations Resolution 598 that called for an immediate ceasefire.
The war began in September 1980, when Iraqi leader Saddam Hussein ordered his army to invade the Iranian territory of Khuzestan that Hussein coveted for its oil and ethnic Arab population. Iraq became bogged down just inside the border, and for the next eight years, the war continued along the border with neither side gaining much territory or advantage. The Iraqi effort, financed by Saudi Arabia and Kuwait, was characterized by ballistic missile attacks on Iranian cities, chemical warfare against Iranian civilians and hundreds of attacks on tankers in the Persian Gulf. Iran also used missiles, mines and gunboats to attack ships and oil terminals in the gulf and employed human waves of conscripts in ground attacks, often young boys taken off the streets. By 1982, Hussein sought a peace agreement with Iran, but the Iranian leader Ruhollah Khomeini refused to stop fighting and instead sought to overthrow Hussein's government.
It is impossible to determine the exact number of casualties in the war, but estimates of roughly 500,000 killed on both sides and another 500,000 injured are reported. Almost $230 billion was expended in the war effort, and $400 billion was suffered in damages.