For more detailed information about each of the classes:
Classes in MMORPGs like World of Warcraft generally fall into one or more general roles, though those roles often overlap and distinctions between them can be somewhat arbitrary. This is not intended as a comprehensive guide to each class -- there are links to very detailed articles of each class at the bottom of this page -- but as a guide to how each class contributes to a Party of characters playing as a group.
As anyone who has ever started playing a MMORPG has quickly learned, there is a lot of jargon used within the game. Hopefully this guide will also serve to explain some of the role-related jargon that players will often encounter.
The most clearly defined role is that of the Tank. Tanks take on the role of absorbing damage, both by having large health pools and strong armor or other defenses. They also need to be able to attract the attention of enemies and keep other party members from being attacked.
Conversely, a character focused mainly on dealing large amounts of damage would be referred to most often as a DPS (short for Damage Per Second, the quantitative measure of their damage dealing ability) or occasionally as a Damage Hose or just Hose (a metaphor for how they 'spray' or 'pour' out raw damage).
The next two roles, Buffers and Debuffers, have similar yet diametrically opposed roles as well. The former can enhance the effectiveness of friendly targets with a positive Buff, and the latter limit the effectiveness of enemy targets with negative Debuffs.
Healers have the role of keeping friendly targets alive. They are really a subcategory of Buffers (since dead teammates are completely ineffective), but even though the role of Healer is a very specific one, it is one of such critical importance that it is considered a role unto itself.
Also of critical importance (though often undervalued) is the Crowd Control role. This role is in essence a narrow and extreme version of Debuffer as an enemy temporarily removed from combat is completely ineffective.
The last role mentioned here would be Utility, a catchall of sorts that describes those abilities that fall outside the previously listed ones. While the previous roles are all very much combat related, Utility can often involve non-combat abilities.
How Classes in World of Warcraft Fill Those Roles[edit]
Seldom does a Class or Character in a group fill only one role; some fill one primary role, some may switch roles throughout combat, and some might fill many roles at once. In fact since nearly every player will spend at least some of there time exploring World of Warcraft alone all characters must have some workaround that allows them to fulfill each role in some way (Non-Healers, for example, can eat food to refill their heath between battles or just wait for it to slowly refill on its own, and Mages, who with their low armor values make poor Tanks, might use their crowd control skills to keep from getting hit in the first place). Knowing what role you’re likely to fulfill and when to switch roles is what separates an experienced party member from a novice. Below is a general description of what roles each class can expect to fulfill.
Druid[edit]
Druids are by far the most dynamic of the classes, overlapping with every possible role in some way, and you can expect to change roles several times when grouping. A true hybrid class, Druids have no central role but instead use shapeshifting to change roles as situations merit. While in Bear form or Dire Bear form druids make good Tanks, in Cat form they can fulfill the role of DPS, in normal form they can make good Healers, and in Moonkin form (which takes a large investment in the Balance talent tree to use) they can make good ranged DPSers. The spell "Mark of the Wild" is a valuable buff for party members, and "Enroot" can be used for crowd control while outdoors. Movement form, which gives them a boost to their running speed, is highly valued in the Capture the Flag battleground and would fall under the Utility heading.
Hunter[edit]
Hunter is a hybrid class that overlaps many group roles. They can capture creatures and train them as pets, and these creatures can be used to Tank enemies as well as inflict some damage. They can lay traps that give them some Crowd Control and Debuff abilities. And they can learn to use Talent Points to become better at ranged or melee DPS.
Mage[edit]
Mages are the main ranged DPS class, able to dish out large amounts of damage at a distance. Their Crowd Control skills are also considerable (arguable the best of any class) as they can use the Polymorph spell to Sheep one enemy (temporarily turn the enemy into a sheep, unable to do anything but slowly recover health and mana) and several Frost spells that allow them to slow enemies down or completely root them in place. It should be noted that those Mages that invest heavily in Fire talents are better at DPS, and those that invest in Frost are better at Crowd Control. Their ability to use magic to summon food and water, and to teleport characters to distant locations provides additional Utility.
Paladin[edit]
Paladins are a hybrid Tank/Healer class, available only to the Alliance. They can wear any type of armor (at level 40 or higher) and have a large enough Health pool to Tank effectively, and they can cast many healing spells and even resurrect fallen comrades making them good backup Healers. Their Auras and Blessing also make them good Buffers. Though not as good at dealing damage as some of the other classes, they do deal enough damage to have a significant impact on most battles.
Priest[edit]
Priests are the most pure Healers/Buffers in WoW. They can cast many different healing spells, several Buffs and the highly valued "Power Word: Shield" which temporarily prevents all damage from hitting a friendly target. Their lackluster ranged and melee damage dealing abilities makes them a challenging class to play solo but their healing abilities make them highly sought after party members.
Rogue[edit]
In general, Rogues can deal more damage than any other class, making them the most DPS oriented class in WoW. (There may be some debate as to weather Mages or Rogues are better at DPS, especially at lower levels, but at later levels, a.k.a. Endgame, Rogues most often do more damage. If Mages have a DPS advantage it is largely because Mage damage is mainly ranged and Rogue damage is mainly melee.) Rogues also have the ability to sneak up and Sap an enemy, giving the class a bit of Crowd Control, but this ability is not always successful and usable only once at the beginning of each combat. Lastly Rogues have unique Utility in that they are the only class able to pick locks, an ability needed to finish some quests and to open lockboxes.
Shaman[edit]
Shaman are a powerful hybrid class available only to the Horde. Many of their skills involve Buffing and Debuffing, often through ‘‘Totems’’ that are placed on the ground and affect any target within a certain range.
Warlock[edit]
Warlocks are a hybrid class with access to many spells and the ability to summon Demons as pets. Their "Curses" and "Shadow Word"s make them the closest thing to a dedicated Debuffer class in the game WoW. Generally considered the least powerful class (and as of late 2005 the least played class on most servers including the authors); there is no clear role at witch they excel. They do have versatility; they can summon several different types of demons (depending on their level) and each type has its own strengths and weaknesses. For example, Imps add more DPS, Voidwalkers can Tank somewhat effectively and are semi-disposable (unlike a Tank player) and their Fellhunters have some crowd control skills and are particularly bothersome to enemy magic users. They can also summon players to their present location, and give another player a "Soulstone” once every half-hour that allows a player to resurrect themself.
Warrior[edit]
Warriors are the best Tanks in WoW. In addition to having large Health pools and high Armor values they also have skills like "Taunt" which can keep enemies from attacking other party members by convincing them to attack the warrior. (This could be considered Crowd Control, as it controls where enemies direct their attention, but it is so vital to the role of a Tank that most players would consider it a Tanking ability.)