Simone de Beauvoir was a French philosopher and feminist whose work significantly influenced modern feminist thought. In her seminal book, *The Second Sex*, published in 1949, she explored the construction of women's identity and the societal roles imposed on them. Beauvoir argued that "one is not born, but rather becomes, a woman," emphasizing that gender is a social construct rather than a biological fact. Beauvoir's ideas challenged traditional views of femininity and advocated for women's liberation and equality. Her philosophy laid the groundwork for later feminist movements and thinkers, including Judith Butler and bell hooks, who expanded on her concepts of gender and identity.