Ethereum has a metric system of denominations used as units of ether. Each denomination has its own unique name (some bear the family name of seminal figures playing a role in evolution of computer science and cryptoeconomics). The smallest denomination aka base unit of ether is called Wei. Below is a list of the named denominations and their value in Wei. Following a common (although somewhat ambiguous) pattern, ether also designates a unit (of 1e18 or one quintillion Wei) of the currency. Note that the currency is not called Ethereum as many mistakenly think, nor is Ethereum a unit.

In Haskell the Ethereum unit system presented as set of types: Wei, Szabo, Finney, etc. They are members of Unit typeclass. Also available standart Show, Read, Num operations over Ethereum units.

> let x = 1.2 :: Ether
> toWei x
1200000000000000000

> let y = x + 2
> y
3.20 ether

> let z = 15 :: Szabo
> y + z

interactive:6:5: error:
   • Couldn't match type ‘Network.Ethereum.Unit.U4’
                   with ‘Network.Ethereum.Unit.U6’
     Expected type: Ether
     Actual type: Szabo