Existentialist philosophy begins with a recognition that human beings exist before they define themselves. Thinkers like Sartre, Heidegger, and de Beauvoir wrote that people are not born with a fixed identity. Each life unfolds through action, choice, and responsibility. Existence is a project to be lived. There is no external script to follow. The individual is both the author and the material of their life. Meaning arises from how one lives, decides, and accepts the weight of their own freedom