Co-Operation

Cooperation (co-op games) is a form of play in which players team up with one another in order to achieve a common objective. The goal of a co-op game is to reduce emphasis on competition and increase emphasis on the social aspects of play

Co-op allows the game's players to play through the entire single player campaign together. In MMO games, some challenges like quests and larger end game challenges can only be completed via intensive co-op play.

Some of the gameplay features which will come under co-op are:

Group Dungeon

Group Dungeons is a type of Dungeon that is designed with 3-5 players in mind. Group Dungeons are instanced and feature tougher enemies and multiple bosses, also challenges like elite quests, and end game challenges can only be done through dungeon grouping. Group Dungeons often feature advanced mechanics that must be managed by the whole group. Proper group composition and coordination is required to overcome the challenges within.

Raiding

Raiding is a feature in MMOs. They are a fun way to interact with friends (or random players) to complete objectives and obtain rare loot drops. At higher levels, raids can be among the most challenging activities in MMOs. In short: Raids form an important part of the “end game” of MMO games, giving high-level players challenging content designed for cooperative play in groups.

All dungeons and raids will have numerous normal enemies and bosses to defeat. Raids are optional end-game content for high-level players, while dungeons are meant for all players of any skill level.

To progress from one raid to another, players must first unlock the required gear. To receive better gear, players must first complete quests and normal dungeons to obtain gear that will let them into heroic dungeons, the LFR (Looking for Raid) system, and so on.