At times it is drunk as a "chaser" after sampling "hákarl", which consists of putrified shark meat, to mask the meat's taste. The word brennivín literally translates into English as 'burning wine', and comes from the same root as brandy, namely brandewijn.
Despite its unofficial status as national beverage and a traditional drink for the mid-winter feast of Þorrablót, many Icelanders do not regularly drink it. The drink has a strong taste and high alcohol content (37.5% ABV), and carries an equivocal reputation: despite the fact that Iceland levies huge taxes on most alcoholic beverages, brennivín is actually one of the moderately priced liquors available in the national alcohol store, Vínbúð, and is thus often associated with alcoholics. It's very difficult to find in the United States.
Brennivín is similar to Scandinavian Akvavit, especially the Danish variety, called brændevin. In Swedish it is called brännvin. The steeping of herbs in alcohol to create Schnapps is a long-held folk tradition in all Scandinavian countries. Brennivín is featured in the Halldor Laxness novel Iceland's Bell.
The label is black and was originally designed to discourage people from drinking the beverage. It used to have the letters ÁTVR inside the circle but now it has been replaced by a coastal outline of Iceland.
It has been a long time since I've tasted a shot... and one must definitely treat it with respect. It makes a fetching photo though, all iced up and ready to go. Cheers.