Bitters give digestifs their distinctive bittersweet flavor, thanks to their herbs and spices. High in alcohol and flavor, only a dash is needed to transform your cocktail from average to astounding.

Angostura bitters are famous for their inclusion in whiskey cocktails, such as the Manhattan or the Old Fashioned. When asked to choose the greatest bitters available, Brad Thomas Parsons (author of Bitters: A Spirited History of a Classic Cure-All) responded, "If there can truly be only one, it has to be Angostura bitters."

Since 1824, Angostura aromatic bitters have been created with the same well-guarded recipe. Parsons pointed out that if you only see one bottle of bitters at a bar, it's most likely Angostura. He added that it's one of the most versatile bitters: "It will instantly add a hint of complexity to a cocktail, helping unite seemingly disparate ingredients."

The name of these bitters comes from the town where they were initially made, Angostura, Venezuela (since renamed Ciudad Bolívar).

Parsons insisted that any cocktail enthusiast should keep at least three bitters in rotation at home: Angostura, orange flavored bitters and Peychaud's -- which is comparable to Angostura, but with a sweeter taste and floral aroma.

For example, the Sazerac is the official cocktail of New Orleans, and it cannot be made without Peychaud's Bitters. In 1838, Antoine Amedie Peychaud created the Sazerac with a secret family recipe for Peychaud's Bitters, according to the Sazerac Company. It has continued to delight the Big Easy ever since.

Campari is one of the greatest potable bitters. The history of Campari began in 1860; it was first colored with carmine dye, derived from crushed cochineal insects. For over 150 years, this Italian, ruby red beverage's complex flavor has distinguished it as a bartender's brand. It achieved fame in the 1960s and 1970s and has recently experienced a return to prominence.

Fee Brothers
Previously a winery, Fee Brothers achieved new heights of recognition when they started producing bitters in the 1950s. Fee Brothers has become a staple in the cocktail world, with a large variety of flavors: old fashion, orange, peach, mint, lemon, grapefruit, rhubarb, cherry and whiskey barrel aged.

Jeff Josenhans, mixologist at the U.S. Grant Hotel, says, "I like the entire Fee Brother's line, simply due to the range of styles. Their Barrel Aged Bitters I consider to be the quintessential American bitters. Unbeatable in classic American whiskey cocktails."

The Bitter Truth
In 2006, Munich bartenders Stephan Berg and Alexander Hauck started producing and distributing The Bitter Truth. They had considerable experience producing homemade bitters for bars and were disappointed with the scarcity and inferior quality of bitters in Germany.

Their first two products were orange and old time aromatic bitters, but they have since expanded. Aaron DeFeo, mixologist for Casino Del Sol, a resort in Arizona, lauds Bitter Truth's celery bitters for the ability to completely transform a cocktail.