Basic information for those wishing to get started in World of Warcraft. This is not meant to be exhaustive, merely to cover the most basic info.
Some basic terms that are useful to understand (this is not meant to be exhaustive):
There are two playable factions: the Alliance and the Horde.
There are six races for the Alliance: Humans, Dwarves, Night Elves, Gnomes, Draenei, and Worgen.
There are six races for the Horde: Orcs, Trolls, Tauren, Forsaken (Undead), Blood Elves, and Goblins.
A seventh race, Pandaren, can choose to join either the Alliance or the Horde. The choice is made early on and is irrevocable. (within the game. You can always pay for a faction/race change and simply choose a Pandaren of the opposite faction if you *really* want.)
The faction you choose dictates who you can communicate and group with. Alliance races cannot group or talk with Horde races.
There are eleven classes to choose from: Death Knight, Druid, Hunter, Mage, Monk, Paladin, Priest, Rogue, Shaman, Warlock, and Warrior.
Certain classes are limited to certain races, while others can be played by any race.
There are three primary roles characters fulfill: Tank, Healer, and Damage. Some classes can fulfill multiple roles through their specialization (spec), while others just provide different styles of fulfilling one or more roles.
If you want to tank, you can be a:
If you want to heal, you can be a:
If you want to focus on damage, you can be a:
There are four armor types: Cloth, Leather, Mail, and Plate.
Some classes start at a lower armor type, then graduate to their final armor type at 40.
Classes that can wear multiple armor types get a passive bonus at level 50 for wearing their highest armor type, so there is no reason after this point to seek armor of a lower quality.
You wear Cloth if you are a:
You wear Leather if you are a:
You wear Mail (start at leather through level 40) if you are a:
You wear Plate if you are a:
As with armor, your ability to equip a weapon doesn't automatically indicate that you should equip that weapon. Right now, only Hunters should wield a bow in combat, because only Hunters will have a full set of attacks to take advantage of using a bow. For everyone else, look at what your primary stats are, your passive abilities, racials, and what you can equip. That will tell you whether you should be dual-wielding (i.e., Rogues, Fury Warriors) using a single 2-handed weapon (i.e, Feral Druids, Retribution Paladins), or using a 1-handed weapon and shield (i.e. Protection Warriors, Protection Paladins).
There are 5 attributes: Strength, Stamina, Agility, Intellect, and Spirit. Strength, Agility, and Intellect will increase stats that increase your damage (Attack Power for the first two, Spell Power for the last). Strength will increase Parry rating for strength users. Agility will increase Dodge rating for agility users. Stamina is a given stat on pretty much any armor or weapon you come across, but tanks will want to consider if they want/need more of it through gems/enchants. Except for Spirit, primary stats cannot be reforged. Spirit is treated like a secondary stat for reforging purposes. Spirit is primarily a stat for healers. It boosts mana regeneration, and for certain specs adds to Spell Hit rating at a 1:1 ratio.
You will be getting Strength on your gear if you are a:
Notice how right now, all the classes that make use of Strength also wear plate.
You will be getting Agility on your gear if you are a:
Agility classes will be wearing leather or mail.
You will be getting Intellect on your gear if you are a:
Intellect users span the entire spectrum of armor.
The secondary stats Hit, Expertise, Critical (Crit), Haste, Dodge, Parry, and Mastery are acquired in rating. Spirit is treated as a secondary stat for reforging purposes. Only secondary stats can be reforged.
PvP Power and PvP Resilience are stats specifically for PvP (as the name aptly indicates). You will gain nothing from these stats in PvE.
If you are a Tank, you will want: Hit, Expertise, Dodge, Parry (except for Guardian Druids), and Mastery.
If you are a Caster DPS, you will want: Hit, Critical, Haste, Mastery.
If you are a Melee DPS or Ranged Physical DPS (currently only Hunter), you will want: Hit, Expertise, Critical, Haste, Mastery.
If you are a Healer, you will want: Spirit, Critical, Haste, Mastery.
Each character will require its secondary stats in different degrees. For example, one spec may favor Mastery primarily, while another might favor Haste. Everyone who has to attack an enemy will want to reach the necessary Hit (and Expertise where applicable) cap for the content he or she is pursuing. This keeps your attacks from missing or being dodged/parried.
The Hit and Expertise caps for physical damage (DPS and Tanks) are 6% for Heroic Dungeons and 7.5% for Raids.
The Hit caps for caster DPS are 12% for Heroic Dungeons and 15% for Raids.
Expertise rating translates 1:1 to Spell Hit rating (7.5% hit and 7.5% expertise will mean 15% Spell Hit for these specs). This is primarily for those specs that need both Spell Hit and Expertise. If your spec doesn't need Expertise, there's usually better ways to get Spell Hit.
Spirit translates 1:1 to Hit for Healers and caster specs of classes that can be healers.
Some races get boni to Hit and Expertise that give them less needed rating to reach the necessary caps. Check your racials!
Secondary Stats (and Spirit) on an item can be reforged to another secondary stat that is not already on that item. Use this to help balance your stats in a way most beneficial to your character.