This is a test based on the "Big Five" personality factors. They are Extraversion, Agreeableness, Conscientiousness, Neuroticism, and Openness. The degree to which you exhibit each factor can say a lot about your personality. The Big Five or Five-Factor model is based on many years of empirical research rather than on an underlying theory.
Update: I have (hopefully for real this time) eliminated the 32 binary "types" and now simply report the scores in each category. This is to represent the fact that the five factors exist on a continuum rather than as black and white categories.
This is my first test, and I'm always looking to improve, so let me know if you have any questions, comments, or constructive criticism.