Jean-Paul Sartre, in his seminal work "Being and Nothingness," argued that existence precedes essence, meaning that our existence as individuals is prior to and independent of any predetermined essence or purpose.

In "The Stranger," Meursault, the protagonist, confronts the absurdity of life and chooses to embrace it rather than succumb to despair or seek meaning where there is none.

Kierkegaard's concept of "angst" encapsulates the feeling of dread and anxiety that arises from the recognition of the uncertainties and limitations of human existence.

In his novel "Nausea," Jean-Paul Sartre delves into the existential experience of nausea as a manifestation of the meaninglessness and absurdity of existence.

Existentialist thinkers emphasize the importance of authenticity, which involves living in accordance with one's true self, values, and beliefs, rather than conforming to external expectations or societal norms.

Jean-Paul Sartre's famous phrase "condemned to be free" captures the existentialist notion that humans are inherently free and responsible for their choices, even in the face of difficult circumstances.

In "The Plague," Camus uses the plague as a metaphor to explore the absurdity and meaninglessness of human existence, as well as the resilience and solidarity of individuals in the face of adversity.

Kierkegaard's concept of "the leap of faith" involves a blind leap into the unknown, a commitment to a belief or course of action without relying on rational justification or evidence.

Albert Camus, in his philosophical essays and novels, extensively explored the concept of "the absurd," arguing that the inherent meaninglessness and irrationality of the universe is a fundamental aspect of human existence.

The concept of "being-in-the-world" in existentialism emphasizes the subjective experience of existence and the way individuals perceive and interact with the world around them.

Søren Kierkegaard explored the idea of "transcendence," suggesting that humans have the potential to transcend their finite existence through faith, commitment, and a leap of faith.

In "No Exit," Sartre uses the confinement of the characters in a room to symbolize the existential isolation and alienation that individuals experience in modern society.

Friedrich Nietzsche famously proclaimed "God is dead," emphasizing the decline of traditional religious beliefs and values and the subsequent need for individuals to create their own meaning and purpose in life.

In "The Fall," Clamence represents the existential guilt and self-condemnation that individuals experience as a result of their actions and choices.

Kierkegaard's concept of "the three stages of life" involves the aesthetic stage of immediate pleasure, the ethical stage of duty and responsibility, and the religious stage of faith and commitment.