The "N" word...

what is the "N" word? to many people its a greeting to one another, to others its just an offensive term which we should never use. What im confuse about is how people wanna get ride of this term but yet use it in there everyday life. so is there an exception in using the "N" word? is there a time of day that's ok to say it freely? i hear it everywhere in school.from classroom to classroom but it doesn't seem to bother anyone.i don't get it? we watched a couple of clips in English class and they brought the "N" word out to life. everybody knows the history behind the word so what gives? i don't like being called a wetback because im not, nor somebody calling me a beaner. its rude and offensive. so im asking everybody out there, give me an answer to this so-called "N" word exception....