Blizzard will add Connected Realms to massively multiplayer online role-playing game World of Warcraft some time after the release of Patch 5.4.
A Connected Realm is a set of two or more standard realms that have been permanently linked and behave as if they were one cohesive realm.
If you're playing on a Connected Realm you'll be able to join the same guilds, access a single Auction House, run the same raids and dungeons and join other players to complete quests.
Blizzard said it decided to add the feature because, over time, shifts in player population have created a "less-than-optimal play experience" for those on less popular realms, making it tougher to beat group content.
"Our goal with Connected Realms is to give players on lower-population realms more opportunities to group up, compete, and connect with other players to take on Azeroth's bigger challenges," Blizzard said on Battle.net.
"That sort of interaction is a big part of what makes World of Warcraft fun, and this feature will help us deliver that experience to even more players."
Last week Blizzard announced that the number of World of Warcraft monthly subscribers had dropped to 7.7 million - comparable to the audience the MMO had in 2007, shortly before first expansion The Burning Crusade helped it break the eight million million mark.
The figure marked a notable decline for World of Warcraft in recent times, having fallen fairly steadily from a highpoint of 12 million subscribers in October 2010 - two months before Cataclysm.
Blizzard said it took the decision to add Connected Realms now because of improvements to its cross-realm tech.
"Our cross-realm technology has continued to evolve since it was first developed for joining players in dungeons," Blizzard said. "It's now at a point where we can create seamless worlds made up of multiple individual realms, and we think there are some really positive benefits to that."
Blizzard is yet to decide which realms will be made part of a Connected Realm, but it has decided to connect realms only to other realms of the same type, so, PvE to PvE and so on. It doesn't know how many realms will make up a Connected Realm, either.
"There should be no limitations," Blizzard added. "We want the experience to be seamless, and we expect it work as if you're suddenly part of a much more active realm."