What makes a martini a martini?

Nowadays, what makes a martini a martini? Robert Simonson, who wrote a book about the martini, said, "It's funny: it's strict and loose at the same time."

Everyone seems to have an opinion about the cocktail: "Ingredients, proportions, garnishes – it's all subject to debate," Simonson said. "I'm a purist. I would think it needs to be gin and vermouth. But I'm willing to bend and say, 'Okay, vodka and vermouth as well.' [However,] if there's no vermouth in there, I don't know how you can call it a cocktail."

Simonson says the martini was probably named after a vermouth company. It was invented in America in the 1870s or '80s when bartenders mixed gin with vermouth, a fortified wine made with herbs and spices. "It's a very big player in cocktail history," he said.