A Boston shaker is a popular cocktail mixing tool used by bartenders. It consists of two parts: a metal tin and a glass or another metal tin. The bartender adds ingredients to the shaker, seals it, and shakes to mix the contents thoroughly. This method is effective for creating well-blended cocktails. The Boston shaker is favored for its versatility and ease of use. Unlike other shakers, it allows for larger quantities of ingredients and is less likely to leak. It is often used in conjunction with a strainer to pour the mixed drink into a glass while leaving ice and solids behind.