Eggs have been a key ingredient in cocktails since the colonial era, particularly in the 18th and 19th centuries. Initially, they were used in punches and flips, traditional drinks that combined spirits with sugar, spices, and sometimes dairy products. The practice of using egg whites to create frothy textures in cocktails gained popularity in the early 20th century with the advent of sours and fizzes. The introduction of the Boston Shaker in the late 19th century, which made it easier to vigorously shake ingredients, also contributed to the widespread use of eggs in cocktails. These developments marked eggs as a critical ingredient for texture and taste in the evolving cocktail culture.