Externalization means to put something outside of its original borders, especially to put a human function outside of the human body. The opposite of externalization is internalization.In a concrete sense, by taking notes, we can externalize the function of memory which normally belongs in the brain.In a more abstract sense, by making excuses, we can externalize the guilt associated with our actions.In Freudian psychology, externalization is an unconscious defense mechanism by which an individual "projects" his or her own internal characteristics onto the outside world, particularly onto other people. For example, a patient who is overly argumentative might instead perceive others as argumentative and himself as blameless.Like other defense mechanisms, externalization is a protection against anxiety and is, therefore, part of a healthy, normally functioning mind. However, if taken to excess, it can lead to the development of a neurosis.Externalization can also be used in the context of a corporation. A corporation that externalizes its costs onto society and the environment is not taking full responsibility and ownership of these costs. An example might be the discharge of untreated toxic waste into a river where people wash and fish.