Short, plain explanations of terms you will meet in posts on this site. They are written for a player who has the game installed but has not yet learned the jargon.
Group content
Raid. A large-group instance, usually ten to thirty players, built around several boss encounters. Older raids could hold forty players.
Mythic+. A dungeon mode with a timer and a difficulty level that rises as you finish runs. Players call a run “a key” after the item that starts it.
Delve. A short instance for one player or a small group, played with a computer-controlled companion and finished in a few minutes. Introduced with The War Within.
Renown. A reputation track with a faction in recent expansions. Each level unlocks rewards, and levels are shared by all of your characters.
Combat and roles
Tank, healer, DPS. The three roles in group content. Tanks hold enemy attention, healers restore health, and damage dealers (DPS) defeat the enemy.
Cooldown. An ability with a waiting time between uses. “Saving cooldowns” means holding powerful abilities for the moment they matter.
Raid comp. Short for composition: the mix of classes and roles in a raid group.
Swing timer. The delay between automatic melee attacks. Some Classic abilities and weapon choices work around it.
PvP terms
Battleground. A team objective match, such as capturing flags or holding bases. Rated battlegrounds (RBGs) are organised, ranked versions.
Arena. A small-team elimination match, typically 2v2 or 3v3, with ranked and casual queues.
Skirmish. A casual arena match that does not affect your rating.
War Mode. An opt-in setting that turns on open-world PvP in exchange for bonus rewards.
Honor and Conquest. Two PvP currencies. Honor comes from most PvP play; Conquest comes from rated modes and weekly goals.
Travel, leveling and collecting
Flight path. A flight point you unlock by visiting it once. Later you can fly there from any other point you have unlocked.
Elite. An enemy that is far stronger than a regular one of the same level, often intended for groups. Solo strategies for elite quests explains workarounds.
Transmog. Changing how a piece of gear looks without changing its stats. Many collectors hunt for old sets.
Classic and Season of Discovery. Versions of the game that revisit older rules. Season of Discovery adds new content on top of the Classic world.