The rial is the currency of Iran and, as of 2014, remains the world's least valued currency unit.
The name derives from the Portuguese real (meaning royal in Portugal), which was for several centuries the currency in Portugal (derived from Latin regalis).
Although the "toman" is no longer an official unit of Iranian currency, Iranians commonly express amounts of money and prices of goods in "tomans." For this purpose, one "toman" equals 10 rials. Despite this usage, amounts of money and prices of goods are virtually always written in rials.
The rial was first introduced in 1798 as a coin worth 1250 dinar or one eighth of a toman. In 1825, the rial ceased to be issued, with the qiran of 1000 dinars (one tenth of a toman) being issued as part of a decimal system. The rial replaced the qiran at par in 1932, although it was divided into one hundred (new) dinars.