Basically, introverts and extroverts are personality trades, and they dictate how your brain works, how you act around people, and lots more. You can be both introvert and extrovert, which makes you an ambivalent (a mix of both, I believe), but usually you lean more towards one or the other, and in my case, I think I lean more towards being an introvert.
For example, a lot of the time I'd rather stay inside than go out to a party, and I find it really difficult to talk to new people and meet new people, because I feel really shy and awkward, I even feel weird going to meet up with a group of friends I haven't seen in a while. I'm not sure why but its just kind of how my brain works.
These things don't necessarily make me an introvert, but they are definitely characteristics of the personality and I think you kind of know which one you lean towards more.
I have had a few questions on social medias from people being quite concerned, I guess because they feel quiet and very sensitive and they don't like going out as much, and perhaps they feel a little antisocial, like people don't necessarily see them in the right way or the right light. No, this doesn't make you weird in any way for being the way you are and for being an introvert.
Being quiet and introspective aren't bad qualities to have, I think there is a thing, that extroverts are just seen as the "normal" ones, and in order to succeed in your life and your career, you need to be a big social person, that is super confident and good at talking in front of lots of people, and that is just not true at all, there are so many people that have shaped the world, who have been introverts like Einstein, Shakespeare, JK Rowling, Abraham Lincoln... all these people are introverts, and are all responsible for shaping the world.
Don't be scared for being this way. You are not weird for being the way you are, and you are still capable of doing absolutely amazing things, and I am not making this mean that extroverts are bad, some of my closest friends, and the best people I know are extroverts, but there is this special stigma where introverts aren't as highly guided as extroverts, and it isn't right, you should be able to be as different as you want to be, and as crazy as you want to be, and just be yourself. 
I would really appreciate if you could leave a comment down below telling me if you are either a introvert or whether you are an extrovert, I am just kind of interested to see what you say, and hopefully I will get closer and know you all a tiny bit better.
Thanks for reading, love you guys, stay weird and see you soon! Xx