The clean-tasting mix of herbal, dry gin and bitter, refreshing tonic water has remained popular for over 100 years, securing a spot as one of the world’s most classic cocktails. There aren't a lot of variations on this drink, but you should still pay close attention to brand names and how some brands pair better with each other than others.

A good rule of thumb is to pair older tonic brands with older gin brands, as they both tend to have more powerful flavor profiles that can stand up to each other. Older tonics in particular often have more sugar and acids in them, giving them a powerful flavor, while many newer brands are drier and feature more complex ingredients.

For example, the flavor of traditional London dry gin is clean and botanical with citrus notes, which pairs perfectly with the hints of lemon and a fairly strong bitter flavor of old-fashioned Schweppes tonic. On the other hand, if you're using modern craft gin, then the more subtle craft tonic brands like Fever Tree will let their complexity shine.