Before defining the competency models of employees, the concept of competency should be reviewed first. In the early 1970s, Harvard University psychologist McClelland showed in an article titled "preference of competence over Intelligence" that intelligence test is a poor predictor of a person's success in a job. Therefore, he recommended merits as his selection criteria. In 1982, McClelland and Boyatzis presented the first competency model in the book "the competent manager". Their definition of competence was: a person's root characteristics, motivation, characteristics, skills, social role and the set of knowledge that he uses to perform the task. We must admit that there is no universally acceptable definition of the concept of competence and different definitions have been formed based on the different views and approaches of experts and thinkers. Some of these definitions are mentioned below to clarify the concept of competence and to obtain common concepts. The root of the term merit can be found in the Greek concept of areti, which means knowledge, a kind of moral excellence and being the best.