Existentialism (// or //) is a form of philosophical enquiry that explores the nature of existence by emphasizing experience of the human subject—not merely the thinking subject, but the acting, feeling, living human individual. In the view of the existentialist, the individual's starting point has been called "the existential angst" (or, variably, existential attitude, dread, etc.), or a sense of disorientation, confusion, or anxiety in the face of an apparently meaningless or absurd world.
Existentialism is associated with several 19th- and 20th-century European philosophers who shared an emphasis on the human subject, despite profound doctrinal differences. Many existentialists regarded traditional systematic or academic philosophies, in style and content, as too abstract and remote from concrete human experience. A primary virtue in existentialist thought is authenticity. Søren Kierkegaard is generally considered to have been the first existentialist philosopher, though he did not use the term existentialism. He proposed that each individual—not society or religion—is solely responsible for giving meaning to life and living it passionately and sincerely, or "authentically".
The main idea of existentialism during the World War II was developed by Jean-Paul Sartre under the influence of Dostoevsky and Martin Heidegger, whom he read in a POW camp and strongly influenced many disciplines besides philosophy, including theology, drama, art, literature, and psychology.