Gin and tonic is a classic cocktail made with GIN, tonic water, and often a slice of lime. It is a popular drink in many countries around the world and is usually served over ice. The main ingredient in a GIN and tonic is GIN, which is a distilled alcoholic beverage made from juniper berries. GIN has a strong, distinctive flavor and is usually clear in color. The other ingredients in a GIN and tonic are tonic water, which is a carbonated beverage flavored with quinine, and a slice of lime, which adds a tart flavor to the drink.