Complexity of human personalities can be summarised in 5 traits with acronym OCEAN

Psychometrics is the objective measurement of skills and knowledge, abilities, attitude, personality traits, educational achievements and more.

One of the founding assumptions of psychometrics is that all the complexities of human personalities can be boiled down to 5 simple traits. The traits are called the Big Five personality traits. These traits are known by the acronym OCEAN (or CANOE):

• O: Openness (willingness to engage in new experiences)
• C: Conscientiousness (perfectionism)
• E: Extroversion
• A: Agreeableness (how considerate and cooperative a person is)
• N: Neuroticism (how easily upset a person can become)

References:

• User Friendly (Cliff Kuang, Robert Fabricant), Chapter 9: Peril