'Dude' is a word used mostly by younger people to address their peers. I don't know the meaning behind it, but you use it for friends. It is more commonly used between boys, but girls say it too. It would be inappropriate for a younger person to call an elder 'Dude'. So, use this between people of your age group! but make sure you know them well enough, or it will be weird calling some 'dude' if you just met them. BUT, since it is an slang, it is really unnecessary to say it! ^-^ Personally, I don't say it because I don't think it's really polite. (\(^-^ )/)

Originally it was a term that country folk would call city folk, then from "Dude Rancher", which was a ranch in the country where city folks would come to get away from the busy city for vacation. "Dude rancher" was shortened to just "Dude", and seemed to get more popular when "Bill and ted's Excellent Adventure" came out. Now you may hear it used between males, especially if you forget somebody's name. You could use Dudette for a girl since its slang it doesnt matter really.

Yes, their answers are correct, but it is spelled 'dude'. To me it is not in any way rude or disrespectful, maybe because Americans can be less formal than other cultures. (In fact, maybe the opposite can be true in some sense) This is true also for people I've just met. I have heard somewhere that the word goes back to the wild west day (I guess roughly 1850-1895) but I don't know anything else about this. Maybe you have also picked up on 'man'. 'Hey, what's up man/dude' is an informal greeting.

"Dude" is an informal term of address between males of the same age or by an older male to a younger male. There are people who use it regardless of sex or age, but some people would consider this usage wrong. While you may not want to use it during a job interview, there is nothing wrong with using it on websites like this, where it creates a certain tone of casualness.

That's right. And the rural folks would call urbanites "city slickers". There was a comedy film by that name, from around 1992 or so.