I like the Myers-Biggs tests but they're not in fashion at the moment. They are more than 'horoscopes' (which are totally unbelievable in my opinion) because they are based on generalisations gained from your own answers to a whole series of questions (assuming you answered truthfully), which aim to measure several attributes which in turn gives your type.
Of course there are many flaws but as a generalisation they can give some indicators, which some find helpful.
My own type is INTJ, and when I read my profile it is very VERY much like me (especially the negative bits I don't want to acknowledge!)
The I - E (introvert- extrovert) scale is often mis-understood. It is NOT a measure of how sociable you are, or whether you like people, or whether you are shy. It is a measure of where you get your energy from.
Extroverts get their energy from other people. If they are on their own for a long time they get depressed and ring someone up for a chat or go out for a drink with a friend, and come back much happier for it.
Introverts may be very sociable but get their energy from within, and from being quiet, away from others. I know that's true for myself; I love being around friends but I also find people draining. When I want to re-energise I go off to be alone and draw great strength and refreshment from that, before re-joining normal life again.