Just as the name says, bitters are an alcoholic spirit with a bitter or bittersweet flavor made from a mixture of plants and herbs. Bitters were originally sold as medicine since they are known to aid digestion. Many popular and retro cocktails contain bitters but only in small amounts since the flavor is extremely potent. There are many types of bitters, so be sure you are using cocktail bitters before you add them.
The Manhattan is arguably the most popular drink to use bitters. The flavor of the bitters is very prominent since it is a simple drink. There are many variations on the drink, but Manhattans are commonly made using 2 oz. of whiskey, rye or bourbon, 3/4 oz. of sweet vermouth and 1 dash of bitters. Stir the mixture, pour it into a glass and top it off with a maraschino cherry.
Metropolitans are similar to Manhattans or Cosmopolitans but have some variations. A Metropolitan can be made with 1 1/2 oz. of brandy, 1 oz. of sweet vermouth, 1/2 tsp. of simple syrup and 2 dashes of bitters. Just as you would with a Manhattan, pour the mixture into a glass and top with a maraschino cherry.
Whiskey Swizzles are often served after dinner in order to aid digestion; hence, why they contain bitters. A Whiskey Swizzle can be made with 2 oz. of whiskey, 1 1/2 oz. of lime juice, 3 oz. of club soda, 1/2 tsp. of simple syrup and 1 dash of bitters. Pour over ice and serve with lime garnish.
Old Fashioneds were created in the 19th century. Their simple recipe and delicious flavor have made them a cocktail favorite that has withstood the test of time. Mix 2 oz. of whiskey with 2 dashes of simple syrup and 2 dashes of bitters. Pour over ice and serve with a maraschino cherry or a slice of orange.