Absinthe is historically described as a distilled, highly alcoholic (45–74% ABV / 90-148 proof) beverage. It is an anise-flavoured spirit derived from botanicals, including the flowers and leaves of Artemisia absinthium ("grand wormwoom"), together with green anise and sweet fennel, and other medicinal and culinary herbs. Absinthe traditionally has a natural green colour but may also be colourless. Green absinthe gets its color from the green pigment found in the chlorophyll of herbs such as, roman wormwood, hyssop and lemon balm. Absinthe is referred to in historical literature as la fée verte -- the green fairy!
One of absinthe's most notable characteristics, aside from its mysterious green color, is the absinthe louche. This is when ice-cold water is added to absinthe and the mixture turns milky opalescent. The louche occurs due to the essential oils coming out of suspension from the alcohol as the ratio of water to alcohol increases. Real absinthe will produce a slow building louche that turns milky white. After the louche the aromas and flavors will open up and you will experience the full profile of the absinthe.