What is madam cj walker famous for?

While the person who first answered this question wrote "madam c.j. walker is famous for inventing the hot comb". . .this statement is not true. Madam Walker did NOT invent the hot comb. Hot combs appear in Bloomingdales and Sears catalogs as early as 1890 when Madam C. J. Walker was still Sarah Breedlove McWilliams, a poor washerwoman, and long before she began her hair care business in 1906.

Source: On Her Own Ground: The Life and Times of Madam C. J. Walker by A'Lelia Bundles
and www.madamcjwalker.com