Why might understanding the psychology of personality be a valuable tool?

          Personality psychology is the scientific approach of studying psychological means that make individuals unique in regard to other individuals (Friedman & Schustack, 2011). Therefore, understanding the psychology of personality is a valuable tool that enables an individual or individuals to gain an understanding of why an individual is unique in regard to being different than another individual, and enables an individual to gain an understanding of an individual's or individuals' thought processes and why particular behaviors occur that are displayed by such an individual or individuals. For instance, psychologist through an understanding the psychology of personality are able to understand and implement treatments or therapy numerous clients in appropriate means designed for each particular individual instead of being designed as one approach for everyone.  

Reference

Friedman, H. S., & Schustack, M. W. (2011). Personality. Classic Theories and Modern Research (5th ed.). Allyn & Bacon.