The World of Warcraft site has been updated with a preview of a new featuring coming with the Battle for Azeroth expansion in August. Communities allow players to "create, manage, and join multiple groups of friends and family". These groups can be themed around anything such as pet collection, class communities, role playing, PvP or anything else that comes to mind. Communities can also be created "cross game".
Communities you create are open to same-faction characters from any realm within your region. You’ll be able to invite characters directly, provide a code, or send an invitation link to those you would like to invite to your newly-created community. You’ll also be able to create calendar events specific to your community and use Quick Join to hop into groups together.
Check out the full preview on the World of Warcraft site.