A classic Irish coffee consists exclusively of hot coffee, Irish whiskey and sugar, with cream (proper cream, not "Irish cream") floated on top. Irish coffee can be considered to be a variation on hot toddy. It is made as follows:
Pre-heat coffee glass with hot water and empty. Add one ounce of whiskey to glass and fill near to top with slightly sweetened coffee. Float cream (which may be whipped, but is usually a pouring cream, added by pouring it onto the back of a spoon, resting on the coffee's surface) on top.
The sugar is necessary, or the cream will not float. Nutmeg, cinnamon, or another spice may be added, but are not usual.
An alternative version, more properly known as "Bailey's Coffee", adds an ounce of Baileys Irish Cream, a liqueur to the mix, or may replace the whiskey with the Baileys altogether.
The Irish coffee, or so the lore would have it, was invented at Foynes, the precursor of Shannon International Airport in the west of Ireland as a warmer for trans-Atlantic in the 1950s.
See also: list of cocktails