Alteration of hair color from blonde to brown, referred to as "dying blonde hair brown," is a widely practiced cosmetic procedure. An example is the notable transformation by Hollywood actress Marilyn Monroe when she changed her natural blonde hair to a dark brunette shade.
The popularity of this hair alteration stems from its ability to refresh appearance, conceal unwanted grays, and cater to personal style preferences. The advent of synthetic hair dyes in the early 1900s revolutionized the hair coloring industry and made the process of dying blonde hair brown more accessible and convenient.