My friends. Didn't take much thought for that one.
High School - I wasn't super close with anyone. I floated around from group to group and had a few friends that I hung out with after school, the weekends and summer holidays. I am close to one person I graduated with and she's actually my maid of honour.
University - Here is where I got thrown into a dorm full of girls. Forced to make friends or enemies. I grew up sort of an only child (my sisters are much older than me), so I was very used to being on my own. Living with a roommate, on a floor with 24 girls, 3 floors to a dorm is quite an experience. Out of that, I met some fabulous people. We all came from different places, thrown together, and came out as friends. Sadly, University ended, we all went different ways and I have only seen 2/5 of them in the past 4 years. I miss talking to them and seeing them and hanging out. I miss walking over to their house/apartment just to say hi.
Living in the city, it's hard to make new friends. Your friends become those people you work with. Those are also the people you probably don't want to spend time outside of work with because you saw them all day. I think I have more friends online than I do in real life. That makes me incredibly sad.