jealousy or pitty I think.

I’m guessing you mean like calling people/groups of people the “drama kids” or the “brains.” That’s just how high school is. It stops after high school when you get to college.
I think it happens in high school because you have the same people moving through school with you for four years. (Or in my case, more like six years from 7th to 12th since we had one high school where everyone meshed.)
In college, you don’t know people long enough/well enough to label them. Plus, does anyone really care in college anymore? (Did anyone really care in high school? Cause I didn’t.)

Self validation…....You compare yourself to your peers and in an effort to convince yourself – and others – that you come out on top, you focus on the negatives that can make the others seem lesser than you.
– Not a desirable behavior, but real nonetheless.

Insecurity

I don’t call it judging as much I call it comparing.

I would call it “High school”

I think it only gets worse after high school and even worse after college. I find that the more people I meet the more they want to compare salary, houses, cars, hobbies and such. It breaks them into a social category where they feel safer or more open. I even see it happen here on this site to a certain degree. There are some people that tend to look down their noses and their are some people that tend to pick their nose and some people who just don’t care. It is life and I don’t see it as such a bad thing, hell….I am guilty of it.

Because its fun! EVERYONE judges everyone else!
its a part of life so deal with it.

ok i am in high school too right now..people tend to judge others more than likely theyre jealous of them or theyre rival enemies..judging others make themselves feel higher..some people tend to judge others wrong by how they look or what they have heard or because of peoples past..its quite stupid