Also known as Indian tonic water, this carbonated soft drink is flavoured with quinine, giving it a slightly bitter taste.

Quinine was originally mixed with carbonated water for medicinal purposes to protect against malaria, particularly in South Asia and Africa (hence the name). However, the British often drank it with gin to make it easier for the palate. This helped create one of the most popular cocktails of all time, Gin & Tonic.

These days, tonic water contains insignificant amounts of quinine, however this is enough to ensure the drink retains its fluorescent properties when placed under ultraviolet light. Accordingly, the drink is less bitter than it would have been when used for medicinal reasons.

While sweet tonic water often contains sugar or corn syrup, diet versions of the drink are typically made with artificial sweeteners.

Tonic water is often also mixed with vodka or dry vermouth and in Europe can be found readily mixed with lemon or lime (called bitter lemon or bitter lime respectively).