From what I understand reading Jean-Paul Sartre's work Existentialism is philosophy that places emphasis on individual existence, subjectivism, and freedom. Everyone is completely free, but freedom does not come without baggage; anguish, forlornness, and despair. According to Sartre, existentialism is philosophy that states that "if God does not exist, there is at least one being in whom existence precedes essence." (Gould, James A.) It seems that Sartre's theory rests on this thesis that existence precedes essence and therefore it should be the basis for any further discussion or understanding of this philosophy. .
To prove this Sartre uses an example an example man or human being, he sys that man first exist, where he is nothing, and then afterwards he defines himself, where he himself will have made what he will be. So if I understand this correctly this means that you need to have existence in order to have essence, so there is no predetermined true thing, it has to already exist in order to become what it is. Therefore man is fully in charge of creating himself as a person, and creating his own future. Subjectivity is also important to existentialism, and by subjectivity Sartre means that while choosing his own self, man also chooses all man. And he states this idea in this citation "to choose to be this or that is to affirm at the same time the value of what we choose, because we can never choose evil. We always choose the good, and nothing can be good for us without being good for all." I"m not sure if I think Sartre is trying to say is that those passionate choices and actions that every individual makes, are influencing choices and actions of others. .
Third and last thing that makes up my definition of existentialism is freedom. "The boy was faced with the choice of leaving for England joining the Free French forces-that is, leaving his mother behind-or remaining with his mother and helping her to carry on.