There are at least three varieties of cocktail shakers:
Ø The Boston Shaker: A two-piece shaker consisting of a metal bottom and glass or plastic mixing glass. The mixing container and bottom are inserted into each other for shaking or used separately for stirring or muddling. A separate strainer, such as a Hawthorn or Julep strainer, are required for this type shaker if crushed ice is used. Without such a strainer, some bartenders may instead strain by narrowly separating the two pieces after shaking and pouring the drink through the resulting gap.
Ø The Cobbler Shaker: A three-piece cocktail shaker that has tapers at the top and ends with a built-in strainer and includes a cap. The cap can often be used as a measure for spirits or other liquids.
Ø The French Shaker: A two-piece shaker consisting of a metal bottom and a metal cap. A strainer is always required for this type of shaker, barring the separation method mentioned above.