I'm still not sure how a friend turns into a best friend. I don't know the exact moment that it happens; is it when you survive your first fight? Or when they're the first person that comes to your mind? While I'm not sure when the exact moment is, I know there are certain signs that tell me when someone is now a best friend.

1. They're the first person you call for EVERYTHING.

Whether you have to complain about school, talk about boy drama, or tell her about your embarrassing (but funny) weekend stories, she is the first person you call.

2. Your closet is her closet.

For whatever occasion, it is an unspoken rule that you can raid each other's closets.

3. You have the worst pictures of each other.

From those crazy nights out, you have the ugliest and most embarrassing pictures of each other. But it's okay because when you look back on those memories you share some good laughs.

4. You don't need to talk to understand exactly what each other is thinking.

A simple eye roll will suffice.

5. They are your professional photographer.

They know all your best angles and will help you find the best lighting because you both know how important it is to get that perfect Instagram picture.

6. You share the same stupid humor.

You know that she'll laugh at the exact same memes and vines as you.

7. They know your deepest, darkest secrets.

You know all their dirt, and you know hers. If she's going down, you're going down with her.

8. You always have each other's back.

Through thick and thin, you're always there for each other.

Best friend, you know who you are.