What is BattleTag?

A BattleTag is a unified, player-chosen nickname that will identify you across all of Battle.net -- in Blizzard Entertainment games, on Blizzard Entertainment official websites, and in Blizzard Entertainment community forums. Similar to the Real ID system, BattleTags will ultimately give players on Battle.net a new way to manage public profiles, find and chat with friends they've met while playing, form groups, and stay connected across multiple Blizzard games.

Battle.net® BattleTag™

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Come on guys! It seems a lot of people are soloing in Diablo III and Blizzard wants to remind people the benefits of team play in Diablo III!



Source:
http://us.battle.net/d3/en/blog/3549...9_20_2011#blog...