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 cups that fit together, while the Cobbler shaker has a built-in strainer and a cap. Both types are essential for crafting delicious cocktails.