Newbie

The term "newb" or nerbie (also spelled noob or n00b - also sometimes said as nub) is a term used often in the gaming culture to describe a player whose skills are similar to one who has only begun to play the game, or hasn't been playing very long.

Origin
The term originally referred to a graduate of the Newberry Medical school, experienced doctors referring to recent graduates as "Newbies". "Newb" is an even shorter term for a person who is inexperienced, or has made simple mistakes. Nowadays, it is used in any multiplayer game that requires skill as a degrading term to describe someone who lacks in skill or is able to succeed with petty tricks. The term is also applied to players that accuse their killers of "hacking" after their own mistakes and/or lack of skill resulting in their death and/or the death of fellow teammates. Noobs are usually said to be the worst players in Halo and use the Noob combo.

Usage
While initially used mainly to describe one whose skills are greatly lacking, it is also frequently used against someone who exploits certain unbalanced features of the game during multiplayer play, such as camping, Janitor/Janitorial, screenwatching/ScreenPeeking and using the "Noob Combo".

However, it can be argued that some tactics traditionally considered to be "noob" tactics require an appreciable amount of skill to use or (in the infamous words of a "Zealot" from Red Vs Blue) that "its a legitimate strategy."

Newb vs. Noob
Though they are pronounced the exact same way, the words "newb" and "noob" have very different meanings.

The term "newb", as said in the above paragraph, is a term used generally to describe a new person or a person who lacks skill in a multiplayer game. An example of such is: "Hey guys, I'm kind of a newb to this game mode, so I am sorry if I die a lot.".

The term "noob", on the other hand, rarely is used to mean a person who is new. The term "noob" is most commonly used as a derogatory term against a fellow player to show anger or annoyance. An example of the term "noob" being used is: "The red team has a friggin' noob sniper owning us.". A denoting sarcastic remark that rebukes the opposing team. This term is usually applied to one who plays the game for a respectable time interval, but he or she still does not meet the standards of a "good" player (ex. dying a lot, walking off cliffs, requiring heavy weapons to kill someone, betraying team-mates for weapons, etc.).