A martini is a classic cocktail made with gin and vermouth, often served with an olive or lemon twist. The exact origin of the drink is unclear, but it's believed to have been created in the late 19th century by bartenders in London and New York City. Over time, the recipe has evolved, and there are now many variations of the martini, including those made with vodka or other spirits instead of gin. Despite these changes, the word "martini" is still commonly used to refer to any straight-up, cold cocktail made with a clear spirit and dry vermouth.