Simplify the following text for a Grade 9 native English-speaking person.
Original: Perhaps the best-known gin cocktail is the Martini , traditionally made with gin and dry vermouth .
Simplified: Today , gin is usually a dry liquor , which means that it is not very sweet . Gin is also very popular in cocktails - two of the most common of these are the Gin & Tonic ( gin mixed with tonic water ) and the martini ( gin mixed with vermouth , usually with an olive added ) .