What Does Friendship Really Mean

Friendship is so complicated. Yeah, recently, I've just realized that the meaning of "friendship" isn't just about hanging out together, laughing hard, doing things together. Well, those things are included but really guys, these aren't the major things why we decided to make a friendship relationship. There's just another thing, and I've been wondering what it is. Finally I found it, and I will tell you in a story.
I have a friend, you can call her as my bestfriend (or at least I consider her as mine) and she also has the other friends. We all share happiness together, and laugh together, by the time it's time to the education year changing. We're now 9 grader and for some reasons (later I'm not sure it's a good idea) that the classes weren't be rearranged. So my friends and I are in the same class again.
Things happened and one of my close friend started making distance, almost all of my friends didn't give a fuck and I thought, "Oh, so that's how they will react to friends they don't really think of."
That close friend befriended another friend who I was thinking she was a slut. But I don't mind. Then another thing happened and WOW it was me who made distance with my friends and this best-friend of mine. And I also found out that 'slut' was the best girl I've ever known and she's so fun to be with, she's kind, she's funny, and the most important thing is that she's trustworthy.
Well guys, from this story we learned many things.
1) Don't befriend guys just because they are bestfriends of your bestfriend. Friendship isn't like buying happy meal, that when you wanna buy chicken you have to buy milo also because it is included.
2) Don't JUDGE people you don't really know. Really, maybe it's easy for you to say, "She's a slut" when you don't know her. But when you start making conversation, you will decide on your own which one's good and which one's bad.
3) Friendship is about loyalty (I may be don't have this as much as it required), trust, and well, having fun together.
That's all from me I hope we are all can find which one is a true friendship and never do the same mistake on it.