The MBTI, short for Myers-Briggs Type Indicator, defines 16 types to which each of us belong, according to our preferred cognitive functions.
>The MBTI sorts for type and each type has a specific function order. Additionally, every type uses all four types of functions, Intuition, Sensing, Thinking, and Feeling. Your type however determines the order and attitude of these functions.
You can test it out at kisa.ca, humanmetrics, odiseajung (en español), mypersonality (requires registration), or John's Personality Test.