Existentialism
Existentialism was coined by Jean-Paul Sartre's statement that for human beings "existence precedes essence." In as much as "essence" is a cornerstone of all metaphysical philosophy and of Rationalism, Sartre's statement was a repudiation of the philosophical system that had come before him (and, in particular, that of Husserl, Hegel, and Heidegger). Instead of "is-ness" generating "actuality," he argued that existence and actuality come first, and the essence is derived afterward. For Kierkegaard, it is the individual person who is the supreme moral entity, and the personal, subjective aspects of human life that are the most important; also, for Kierkegaard all of this had religious implications.
Read more about this topic: Essence