From eccentric and introverted to boisterous and bold, the human personality is a unique, multifaceted thing. Personality refers to a distinctive assemblage of traits—characteristic patterns of thinking, feeling, and behaving. It derives from a mix of inborn dispositions and inclinations along with environmental factors and experiences. Although personality can change over the course of time, one's core characteristics tend to remain steady over a lifetime.
While there are countless characteristics that combine in an almost infinite number of ways, people have been trying to find a way to classify personality into types ever since Hippocrates and the ancient Greeks defined four basic temperaments. Today, psychologists generally define personality in terms of five basic traits. The so-called Big Five are openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism. (A new model gaining momentum incorporates honesty-humility as a sixth key trait.)
For the last hundred years, employers have often sought to apply systematic approaches to employee selection, and they have utilized various assessments of personality characteristics. Currently, the Myers-Briggs Type Indicator and the DISC personality test are used widely. Critics contend that their ways of sorting people into discrete type categories are not valid psychologically and, further, that there is no evidence that the typologies predict anything meaningful about job or life performance.