Create Your BattleTag
If you haven't yet created a BattleTag, be sure to check out these resources and set up your BattleTag nickname as soon as possible, as it will be required to play Diablo III. You can quickly create your BattleTag or use your one free BattleTag change here: https://us.battle.net/account/management/battletag-create.html
Please note that while BattleTag-based cross-game chat will be supported in both StarCraft II and World of Warcraft at the launch of Diablo III, you will only have the ability to send and accept BattleTag friend requests when logged in to Diablo III. This means that in order to chat with a friend in StarCraft II or World of Warcraft using your BattleTag ID, you must first send or accept a BattleTag friend request in Diablo III. We'll be adding in the ability to send and accept BattleTag friend requests in StarCraft II and World of Warcraft in the future.
For more information about BattleTags, be sure to check out the FAQ and website page linked above. We'll have more details to share as development continues, so stay tuned!