In my country. It is very common to say hi! or hello! to a stranger. It is just a polite greeting. For us asking someone (How are you?) is an invitation for more conversation... Salam, Fatima USA

No ... I think that "Hi" is very informal and it will not be good if I am talking to a stranger. I will say ( How do you do ??? or How are you ??? or Good evening. And the best greeting in Islam for all -even stranger or not- is ( Peace be Upon You ).

i say good morning, good afternoon, good evening and goodnight to strangers but it is always polite.. of course this is in Japanese.. there aren't many people who speak english around here. back when i was in Australia I would rarely say hi to someone walking on the street, i would greet them in other ways like 'how are you', 'g'day', 'good morning' etc.

yeah we can say hi for stranger people , why not hhhhhhhhhhh. we can help them to if they need help , without know them .

"Hi" is normally an informal way of Greeting. The best way to greet a person is to say "Hello". It can be used both as formal and informal. Of course if you know the person and you have chatted with him or her before, then its fine to say "Hi" .