A simple highball cocktail made with gin and tonic water poured over ice, then garnished with a lime wheel is called Gin and Tonic. In the early 19th century, the cocktail was introduced to India by British officers. Malaria was a persistent problem in India, so the officers used the cocktail to prevent and treat the disease with the tonic's quinine.

Due to its bitterness and sour notes, this cocktail is hugely popular worldwide, especially during the summer months. One can experiment with ratios of the components, even though suggested ratios of gin to tonic water range between 1:1 and 1:3.

In some countries, it is commonly referred to as Gin Tonic, while people in English-speaking countries often simply call it G & T. Today, the cocktail is so popular that it is celebrated on October 19th, when it is known as International Gin & Tonic Day.