The short 16-question test also defines intermediate personality types, discover if you're an Introvert or Extravert or Ambivert, Sensing and Intuition or In-between (X), Thinking and Feeling or In-between (X), and Judging and Perceiving or In-between (X).
The four-letter result can be compared to the Myers-Briggs Type Indicator™ and other free personality tests like 16 Personalities and Human Metrics.