Personality can be defined as a dynamic and organized set of characteristics possessed by a person that uniquely influences his or her cognition, motivations, and behaviors in various situations. Personality is thought to be determined largely by genetics and biology, by environment and experiences, or by some combination resulting thereof. There is evidence for all possibilities. Contemporary research suggests that most personality traits are based on the joint influence of genetics and environment. One can be identified through the personality. Behavioral theorists typically believe that humans are passively shaped by their environments, whereas humanistic and cognitive theorists believe that humans are more active.

Personality theories differ on whether people can change their personalities (Optimism), or if they are doomed to remain the same throughout their lives (Pessimism).Many critics say that personality is just like a plastic and it stretches across time depending on situation, mood, and places. Personality type refers to the psychological classification of different types of people. In humanistic psychology it is emphasized people have free will and they play an active role in determining how they behave. One’s personality can be tested through two ways one is projective and the other is objective. Projective tests assume personality is primarily unconscious and assess an individual by how he or she responds to an ambiguous stimulus, like an ink blot whereas objective tests assume personality is consciously accessible and measure it by self-report questionnaires. Research on psychological assessment has generally found objective tests are more valid and reliable than projective tests. One can be loved and hated through the type of personality he or she possesses.