Simone de Beauvoir was a French philosopher and feminist, best known for her influential book, *The Second Sex*, published in 1949. In this work, she explored the construction of women's identity and the societal roles imposed on them, arguing that "one is not born, but rather becomes, a woman." Her ideas challenged traditional views of gender and laid the groundwork for modern feminist theory. De Beauvoir was also a prominent existentialist, closely associated with Jean-Paul Sartre, and her philosophical ideas emphasized individual freedom and responsibility. Throughout her life, she advocated for women's rights and equality, making significant contributions to discussions on gender, sexuality, and ethics.