That people differ from each other is obvious. How and why they differ is less clear and is an important part of the study of personality. Personality psychology addresses the questions of shared human nature, dimensions of individual differences and unique patterns of individuals.

That people differ from each other is obvious. How and why they differ is less clear and is the subject of the scientific study of personality and individual differences. Although to study individual differences seems to be to study variance, how are people different, it is also to study central tendency, how well can a person be described in terms of an overall within-person average.   More detail...