A cocktail shaker is a tool used to mix and chill cocktails by shaking ingredients together. Typically made of stainless steel or glass, it consists of two or three parts: a container, a lid, and sometimes a strainer. The shaker allows bartenders and home mixologists to combine spirits, juices, and other ingredients effectively, creating a well-blended drink. There are different types of cocktail shakers, including the Boston shaker and the Cobbler shaker. The Boston shaker features two metal tins, while the Cobbler shaker has a built-in strainer and a cap. Both types are essential for crafting delicious cocktails in bars and at home.