Many bartenders prefer using cocktail olives for garnishing over other garnishes such as cocktail onions and lemon twist. The main benefit being that it adds salt to a cocktail. This is because olive used in cocktails is normally preserved in salt water (brine).
Only green olives are used in cocktails; these are commonly pitted and stuffed with a variety of ingredients, ranging from the extremely popular red pimento to almond, lemon peel, onion, garlic or even anchovies.
The brine, also known as olive juice, is also an integral part of many cocktail recipes.