An introvert is someone who finds social interactions draining and difficult. He/she likes to create a cave for themselves and is perfectly content in it. An extrovert is, obviously, the opposite. He/she is someone who loves and gets energy from interacting with people, not liking solitude in any of its forms. There are people who live comfortably in those extremes, and manage to live life successfully this way.
But that's not most of us. Most of us, out of necessity, interact with others, face-to- face, on a daily basis, while regularly finding ourselves, at times, alone. How well we deal with those situations depends on where we fall on the I/E scale. The more introverted we are, the less likely we are to pursue situations with many people, face-to-face. The more extroverted we are, the more we avoid being alone like the plague.
This is why the social media phenomenon is so popular. It satisfies the introverts by allowing them safe interactions, while feeding the extrovert's constant need to be in touch with others, even when there's no one physically around.
I'm an extroverted introvert. I feel most comfortable in my own company, or in the company of a chosen few. Although I can function in larger settings, even addressing large crowds of people, I have had to acquire that skill which does not come naturally. After having been in those situations, I feel drained and require solitude.
I have to encourage myself to be in large settings; I don't do so enthusiastically. That's the introverted part of me. If I can overcome it, which is about 70% of the time, I do so with method. At a party, I will mingle with one or two people at a time, asking them questions about themselves, taking the focus off me, and surviving it piecemeal; but when I get home from the party, I sigh in relief.
I am just as happy going to a movie alone, as going with my buds. I will overcome this to go to a concert that I love, or to a pub; but I don't enjoy clubs, parades and massive venues. I don't like crowds and get overwhelmed when there is a lot of stimulus and noise around me. That's when I create a safe haven in my head to overcome it, but as a rule, I avoid those situations completely.
Not so oddly, I can address big crowds of people, merely because there is a controlled space between them and me; but I cannot address a large crowd of people at a party. Having that much attention in such close proximity makes me uncomfortable.
Where is this all going?
Knowing these things about myself, allows be both to gauge whether I will attempt an experience or not and to develop tools of coping when I do go for it. It gives me peace of mind. I don't beat myself up when I pass on those situations; and when I do, I navigate them more comfortably.
It's an exercise in self-analysis I highly recommend. :)