A gin and tonic is a highball cocktail made with gin and tonic water poured over a large amount of ice. The ratio of gin to tonic varies according to taste, strength of the gin, other drink mixers being added, etc., with most recipes calling for a ratio between 1:1 and 1:3. It is usually garnished with a slice or wedge of lime. To preserve effervescence, the tonic can be poured down a bar spoon. The ice cools the gin, dulling the effect of the alcohol in the mouth and making the drink more pleasant and refreshing to taste