Let me tell you a question.

Someone once told me, before I had kids, that if you ever have any doubts about whether you are an introvert or an extrovert, you'll figure it out pretty quickly once you have a kid who is the opposite.  If you are introverted like me and my husband, and probably my daughter, that means you get energy from within and from spending time alone with yourself (to re-fuel).  If you are extroverted, like my son, that means you tend to need other people to feel energized and re-fueled.

It's a spectrum I'm sure, but in a nutshell that's what the terms  mean to me.

For me, most of the time, parties daunt me.  If they don't daunt me, they tend to drain me. It is not that I don't like parties but I get what I want out of them faster than extroverts. I treasure my friendships but thrive when I nurture them one on one.  I used to really fight against this instinct in me.  I forced myself to be more social than was really comfortable.  Now, especially since my partner is an introvert too, I've become more accepting of that part of myself.

When my daughter was born, her cheery and independent spirit exhibited itself right from day one.  We confused the regular demands of a new child with extroversion and thought for sure she was an extrovert.  Us introverts were not used to all the demands on us for interaction that all kids need.  As she grew though, we realized that she in fact had a similar tendency as us to not really need outside stimulus to energize her.  She could play on her own for long stretches, she would get quite overwhelmed if a party was too loud.  She slept in, even as a toddler.

Then our son was born.  He has all helped us to understand another dimension.  He is an extrovert.  He  does not like to do anything alone.  He asked for some fruit the other day.  The fruit was already cut up and placed on a serving plate.  He was standing beside it and it was within reach.  I told him to help himself.  He insisted that he be served it by me.  Initially, when I got these kinds of requests I would balk, "I'm not your servant, serve yourself.  It is right there." 
We used to view this kind of request as an obtuse demand for attention.

Once we finally started to understand that it was not that he was too lazy to serve himself, but rather that he really would rather have the interaction that would come along with being served we have tried to make a regular effort to accommodate him.  He also has a very hard time doing activities without his sister or without friends around.  If I invite him to come with me to the store to get milk, and his sister decides to stay home their father, he refuses to come along.  At night, he'll wail that he can't sleep until someone comes along and holds his hand and murmurs to him until he can't stay awake any longer.  Okay, so this is what it's like to be extroverted. Poor little mite, stuck with us self-contained folks.  Now that we recognize it, we try our best to be aware of it. We still expect him to do things for himself, which as he grows he too wants to do, but we also are starting to marvel, in many ways for the first time, at what joy comes from sharing with someone else. 

His latest strategy is to lengthen a conversation (and his time with one of us) by saying, "let me tell you a question."  In other words, "stay here, right here, and listen while I think out loud about which question we should talk about but also about all the possible answers.  It will be better that way.  We'll do it together."

For you, my darling, okay, let's do it, I'm listening.