there's a new person at my school and he says "hi" to everyone is that some kind of slang term mean people use on the streets?

OH SH*T

HE'S A REPTILIAN AND HE'S TRYING TO ELIMINATE THE WEAK ONES

RUN, DONALD, RUN!!!!!!!

Hi is a greeting akin to hello but is less formal. He's just trying to be friendly. It is not easy entering a new school where everyone knows everyone else and he knows no-one so try being friendly back to him.

Hi is generally used as a greeting. More used in USA. Hello is used similarly in Britain.

In developing countries like India both Hi and Hello are used. Hi is more informal, while Hello is more formal in such countries.

That is a term meaning hello & is used in most English speaking countries,though it did originate from the USA,but you know that troll.Yes,I looked at your activities and troll is what you are.

No, it's a very, very common greeting. As I'm sure you know.

"Hi" is the short form of "hello" and is probably an effort by the new person to show his friendliness.

It is slang for hello

Maybe he just likes to greet people a lot.