When a person comes to work, brings with him his total personality, his attitudes, likes and dislikes, his personal characteristics and these, in turn, influence the satisfaction he derives from his work. It becomes important to examine how his personal characteristics influence his job. Personal characteristics here refer to such bio-social variables as age, marital status , education, length of service , and income, etc., Job satisfaction is how content an individual is with his or her job. This paper explains the brief concept of Job satisfaction, theories, determinants and the importance of Job satisfaction.