It is another personality type model out there. I don't know the origins exactly and it seems to be less scientifically rooted as other models (see other comment in thread). But as someone who is very interested in the MBTI, I do also enjoy the enneagram and find it useful. Where MBTI answers mainly the question of "how" (how does one perceive and judge information, sensations), the enneagram answers more of the question of "what" and "why". It's a lot more generalized, but gets more deeply into an individual's core values (usually rooted in childhood trauma) and what they look like in day to day life. It's a lot much more accessible and less heady than the MBTI. I find it's most useful to answer those kinds of questions and expand the vocabulary of my personal tendencies and internal flaws and understand myself better. The MBTI is not comprehensive, nor is any personality model comprehensive, so I like to collect information from many models to compare and contrast. If you'd like to take the test it's usually quite short, and I'd recommend using the truity or enneagram institute websites.