Please explain the five-factor model in terms of the characteristics of each factor. How does this approach to personality relate to how you choose a friend by explaining the two most important traits you consider?

The five-factor model, or "big five" personality traits, was developed in the 1980s and 1990s based on lexical hypotheses. The main assumption of this hypothesis is  most of the important human traits are encoded in words of natural languages, and the analysis of the structure of these words leads to a scientifically acceptable personality model. Personality traits are the pattern of behavior, feelings, and thoughts of an individual.

One important thing to be noted is that each of the five personality traits represents two extreme levels, and the majority of the population belongs somewhere in between.

In a five-factor model, the personality is divided into five major traits, which help to predict and explain human behavior. They are,

1. Extraversion: This is also known as surgency.They are characterized by energetic, socially active, assertive, and action-oriented individuals. They like to be engaged in social settings and be the center of attention. Extroverted people talk a lot and show more dominance in group settings.

The extreme opposite of extraversion is introversion, where people love to be alone and independent. This doesn't indicate that they are shy, unfriendly, or antisocial; rather, they need more time alone, less social interaction, and require less stimulation compared to extroverts.

2. Openness to experience: People who are characterized by high openness will have creativity and love adventure and challenges. They seek more changes and show a broad range of changes along with high intellectual curiosity and an openness to emotions.

In contrast, people low in these personality traits are difficult to accept changes, more traditional, closed-minded, and struggle with abstract ideas.

3. Agreeableness: People with this personality trait show high prosocial behaviors like altruism, trustworthiness, empathy, and kindness. They love to get along with people, seek social harmony, and are more optimistic.

The people who are low in these traits seem to be competitive, non-cooperative, suspicious, do not show much interest in helping others, and sometimes become manipulative.

4. Conscientiousness: They are more responsible and duty-oriented people. They have a tendency to control their impulses, be well organized, and engage in goal-directed behaviors. They always prefer to plan and act accordingly.

People who have low conscientiousness are less organized, unstructured, and procrastinate, and they often fail to attain their targets.

5. Neuroticism: They are emotionally unstable, irritable, and show moody behavior. They experience more stress, anxiety, and depression. They have a low tolerance level and get upset easily.

Low neuroticism shows emotionally stable behavior, is relaxed, deals well with stress, and is free from persistent negative feelings.