Ability through Level
Ability - This generally refers to the special actions your character can take to interact with the game world, fight mobs, buff or debuff people, etc.
Alliance - This is a formal or informal group of guilds or clans that band together for a common purpose. Some games support alliances through code. On games that do not, guilds often form alliances and maintain them through web forums or mailing lists.
Avatar - Your in game representation of your character persona.
Build - SEE: Specialization
Clan - Player formed organization that is designed to facilitate teamwork in PvE or PvP. Clans can be simply a group of friends who want an easier way to communicate, or they can be a highly formalized group of individuals with a specific goal (like a raid clan).
Class - Classes are the most common term for the job or profession of an MMO character. The class usually determines the majority of a character's skills and abilities.
Ding - To gain a level or advance your character in some significant way. This term originated from the musical "ding" sound effect most MMOs have when you gain a level. Players would then often announce on a chat channel "DING!" to tell friends they had gained a level. Frequently, people then respond "Grats!" Some people will jokingly refer to this phenomenon as "DING GRATS!"
EXP - See: Experience Points.
Experience Points - Also EXP or XP, these are points that you earn from things like killing NPCs, completing quests, or other tasks. XP is generally used to gain levels, train skills, or somehow represent an improvement in your character's ability or level.
Faction - MMOs often have groups or organizations of NPCs that are called a Faction. Your character then can perform quests or tasks that can improve your standing with that faction (reputation). You can also improve your reputation sometimes by simply killing the right kind of mobs. As you improve your reputation with a faction, you often unlock access to additional content, items, or features. Some factions are diametrically opposed. So gaining reputation with one faction will lower your reputation with another.
Group - A number of players, generally ranging from 1 to 8, who formally join forces to complete shared goals. Groups generally share xp and loot, quest updates, and similar accomplishments. There is typically a group leader who handles invites, loot settings, and dismissals. Raid groups are generally multiple groups that are unified for significant goals (e.g. raids).
Guild - In some games, like Threshold RPG, your guild is your class or profession. In other games, your guild is like a Clan. See: Clan.
Healer - This is an extremely general category of class role that includes any classes or characters that can provide healing to a group. A current absurd trend in online games is to give healers a lot of DPS/damage abilities. This is a lame attempt to make healing classes more popular. People don’t play healers because they want to do damage. If your game is hindered by a lack of healers, find ways to make them more fun or design your game not to absolutely require their presence in every team.
Hybrid - Hybrid classes generally combine two or more aspects of other types of classes. They may combine tanking and dps, support and dps, support and tanking, ranged and melee dps, etc. Unfortunately, hybrid classes tend to be very difficult to balance for most MMO designers, and they often just give up and accept hybrid class inferiority (e.g. Thanes on DAoC). This is a shame, because hybrids appeal to a very large segment of the gaming population and they really should not be ignored.
Level - In level based games, your level is an abstract representation of how powerful or experienced you character is. Typically, a higher level character is more powerful than a lower level character. But in some games, player skill is of such importance that a lower level player can actually be more useful or effective than a higher level one. Sadly, this is pretty rare in the current MMO climate.