Noob: An idiot who thinks they know everything about something and usually complain that more experienced people don’t know anything.
Contrary to the belief of many, a noob/n00b and a newbie/newb are not the same thing.
Newbs are those who are new to some task and are very beginner at it, possibly a little overconfident about it, but they are willing to learn and fix their errors to move out of that stage.
Noobs, on the other hand, know little and have no will to learn any more. They expect people to do the work for them and then expect to get praised about it, and make up a unique species of their own.
Noobs are often referred to as n00bs as a sign of disrespect toward them.