The gin martini, made with gin, dry vermouth, and garnishes, is the definition of a classic cocktail. Hundreds of different cocktails served in a martini glass have been called "martinis," but for me, there's only one definitive version. Serve it well-chilled and use the best ingredients you can find, because the simplicity of the recipe allows for the purity of the cocktail to shine.
Combine the gin and vermouth in a chilled mixing glass. Fill with ice and stir vigorously. Strain into a chilled martini glass. Garnish with olives, and pinch the lemon twist over the martini and discard. Serve immediately.