ettiquette

an AUP is. acceptable use policy- a set of rules and protocol in a buisness or workplace.
when they first give you your laptop at school you have to sign an aup to agree to not to damage the laptop, some examples are damging the laptop, downloading stuff on it, getting on websites you shouldn't be on, hacking into the schools server and what not,pretty much doing anything that would harm the laptop and making it break.

Like in a job place you would probably sign an aup so you would not do stuff that your not supposed to be doing like checking email and etc.
aup's are necessary so that that the job or schools stuff does not get damaged or makes you do your job to the best of your ability.
for instance if i was the boss of an organization i would probably let my employers do whatever they wanted inside the boundries as long as they get their work done

internet etiquette- is pretty much the way you conduct yourself on the internet
netiquette is a combination of internet etiquette. behave as though you are communicating in person. also shouting online is considered rude. and do not flame other people, do not send spam, do not distribute copyrighted material, do not be a coward and remember that your words are open to interpretation.

if an isp collects enough complaints about an account holder, it can cancel that persons account, or they may turn the poster over to the authorities

i think netiquette is important because if it wasn't there then the computer world would be a big mess and no body would want to get on it