The currency in Iran, or the money used, is called the Rial (pronounced ‘reeyaal’). The Rial is like the dollar or a pound in that is made up of 100 pieces, in Iran called dinars. However, due to high inflation one Rial is worth so little that no fraction of it is really used on a day to day basis.
The Rial was first introduced as the currency in Iran in 1798 as a coin. Back then it was worth 1250 dinars. Then in 1825 the Rial ceased to be issued. The Kran of 1000 dinars was then issued as part of a decimal system. The Rial replaced the Kran at par in 1932, although it was divided into one hundred (new) dinars.
When talking money in Iran you may hear the term Toman (Toe'man). The Toman is an old term but is no longer an official currency. However it is is still used on a daily basis in Iran and it refers to the amount of ten rials.
1 Iranian Rial (IRR) = 100 dinars.
Notes are in denominations of IRR 1,000 & 2,000 &  5,000 & 10,000 & 20,000 & 50,000
Coins are in denominations of IRR 5, 10, 20, 50, 100, 250 and 500
In the old times, Coins were available in 50 Dinars (10 Shahi, 1/2 Rial), 1, 2, 5, and 10 Rilas. Bank notes were available in denominations of 10, 20, 50, 100, 200, 500, 1000, 2000, 5000 and 10000 Rials.