American Slang Post
I know that the phrase “what’s up” is really

popular for non-English speakers to know. However, I feel like it has the connotation of just being “cool” or “street slang” or something like that. Actually, Americans use the phrase “what’s up” quite often. It really just means “what’s going on.” So yes, we use “what’s up” as a greeting between friends. However, we also use it in these situations

“I’m sad right now.” “Why, what’s up?”

Answering the phone, if it’s a friend or family member calling, we may say “Hey, what’s up?”

If someone is acting weird, we may say “what’s up with you?” That could be said in a concerned way or a confrontational way, it just depends on context

So, yes we do use it to greet each other but it can be used in other situations. This phrase is casual and should typically be reserved for friends and family