A Martini is an alcoholic drink made classically with gin and vermouth and served with a green olive (when served with coctail onions the drink is called a "Gibson").
It is served chilled, often by ice in a specific shaker, then drained into the signature-style glass.
The ratio of the two liquids is 5:1 (traditionally, 2 and one half ounces of gin to half an ounce of vermouth) usually, though by changing this, a person can make the drink "drier" (more gin) or "wetter" (less gin) depending on his tastes.
Martinis can also be made with other alcoholic bases, the most common
alternative to gin being vodka (often called a Vodka Martini, Vodkatini, or Kangaroo)
Other variations of
the Martini centre around the inclusion of other alcohol or flavours
in the drink.