Big-5 Personality is a grouping of personality traits. Other personality metrics, like Meyers-Briggs, do not have the predictive validity that Big-5 does.
The traits (which can be abbreviated with the acronym OCEAN) are:
This concerns, among other things, the willingness to defy the ordinary. Open people are willing to entertain unconventional ideas, and are eager to partake in unusual or intense experiences.
Concerns the desire and focus necessary to do one's work well. Conscientious people are organized and self-disciplined.
Concerns one's approach to social situations. Introverts consider large social gatherings to be stressful or draining, whereas extraverts would be more inclined to consider such situations energizing.
Agreeableness one's willingness to please and avoid conflicts, and aversion to displaying negativity.
Neuroticism concerns ones approach and inclination towards negative emotion. Neurotic individuals are more inclined to negative emotions and emotional swings.
Each of these groupings can be further divided into sub-groupings.
These traits are predictive of political views, behavior, and life outcomes. These traits can be assessed by a Big-5 personality test.
The variation in these traits between individuals is partially explained by genetics and partially explained by environment. They are relatively stable throughout one's life.