While variations are many, the standard modern martini is made by combining approximately two and a half ounces of gin and one half ounce of dry vermouth with ice in a cocktail shaker or mixing glass. The chilling of the ingredients is done either by stirring or shaking. The mix is then strained and served "straight up" (without ice) in a chilled cocktail glass, and garnished with either an olive or a twist (a strip of lemon peel, usually squeezed or twisted to express volatile citric oils onto the surface of the drink). Capers or cocktail onions are sometimes used as substitute garnishes. An onion-garnished martini is properly known as a Gibson.
Another common but controversial variation is the vodka martini, which is prepared in exactly the same way as a standard martini, with vodka being substituted for gin as the base spirit. In the 1990s, the vodka martini supplanted the traditional gin-based martini in popularity. Today, when bar and restaurant customers order "a martini," they frequently have in mind a drink made with vodka. Martini purists decry this development: while few object to the drink itself, they strenuously object to it being called "a martini." The martini, they insist, is a gin-based cocktail; this variation should be designated as such, with the name "vodka martini" (it may also be called a "vodkatini" or a "kangaroo").
Tequila was originally produced in the 16th century near the location of the city of Tequila which was officially established around the year 1656. A drink named octli was produced by the Aztec people, which was adopted by the Spanish conquistadors when they ran out of their own brandy. About eighty years later, around 1600, Don Pedro Sánchez de Tagle, the Marquis of Altamira, began mass-production of tequila.
As a symbol for cocktails and nightlife in general, the conical martini glass with an olive is often displayed on the signs of American bars.