In video gaming slang, and especially in online multiplayer games, to rank up (sometimes abbreviated r^ in text chats) is to achieve a higher ranking relative to other players. Ranking up may refer both to this and the techniques used to do so, while a rank-up game, rank-up match or rank-up room is a match expressly set up for this purpose.
The term "ranking up" usually implies a direct approach. Gamers who rank up may exploit known game glitches, play with special strategies, or play only in specific matches or against certain other players, to improve their ranks without using or improving their own skill or expertise in the game in general. In this case, it is often considered a form of cheating.
Single player games
In single player games, often a ranking system is also present. High rankings will most likely lead to better rewards or can even unlock features or extra levels. Sometimes, a certain ranking must be achieved in order to succeed a level.
In Hitman, one can achieve a higher ranking by performing as little kills as possible, in contrast to Tenchu, by not using any firearms, by remaining undetected and by not alerting guards of a possible intruder (that being you). The best possible ranking is silent assassin (maximum stealth and minimum aggression). Two other extremes are mass murderer (minimum stealth and maximum aggression) and sociopath (maximum stealth and maximum aggression, best achieved in the Traditions of the Trade mission of Hitman: Contracts).
In the video game franchises Devil May Cry and Ace Combat a grading system using letters is used. In Devil May Cry, the rating goes from SSS to D, with SSS being the highest and D the lowest and with each letter being assigned a single word to represent its value (e.g. in Devil May Cry 3, A stands for "awesome"). In Ace Combat the rating goes from S to C with S being the best and C the worst.
In Grand Theft Auto: San Andreas an overall ranking (which can be viewed in the stats menu) will give the player a ranking (which carry names given to individuals within the criminal underworld such as King of San Andreas, Burglar and Pickpocket) depending on his or her score. This score is influenced by gang members and dealers killed, territories lost or gained, game progress (completing all missions, odd jobs, races and the like will reward the player with a grand 100%), various RPG-style stats including respect and appeal and more. The best ranking, King of San Andreas will not reward anything special, except bragging rights.