Blizzard Entertainment will be introducing a new “Connected Realms” feature in its Patch 5.4 for World of Warcraft, allowing players to play with friends from other realms. The system will connect a set of two or more realms with one another so that they behave as if they’ve been permanently linked. To the players, the linked realms will behave as one, allowing them to raid, group join, and join guilds across other realms.
Unfortunately, the company hasn’t announced or determined which realms will be connected, so there’s still the chance that you won’t be able to play with other friends in other realms. Regardless, the experience will be seamless according to Blizzard, with only indicators in certain areas, such as chat, to show that players are from a specific realm.
Connected Realms won’t be available as soon as Patch 5.4 hits, but shortly after.
Source: Battle.net