Battle.net BattleTag™
A BattleTag nickname is a player-chosen handle that identifies your Battle.net account in Blizzard Entertainment games, websites, community forums, and more. Similar to Real ID, BattleTags give players on Battle.net a way to find and chat with friends they've met in-game, form groups, and stay connected across multiple Blizzard Entertainment games. BattleTag gives you another way to connect and communicate across Blizzard games, without disclosing your Real ID information.
Basics
A player's BattleTag is not unique. You can use any name you wish, as long as it adheres to the BattleTag Naming Policy. Only one BattleTag can be associated with each Battle.net account. Each BattleTag is automatically assigned a numeric BattleTag code, which combines with your chosen name to create a unique identifier (e.g. FallenSlayer#3592). Every Battle.net account automatically receives one free BattleTag change. Once you’ve used your one free change, you will not be able to change it again -- so make sure you choose a nickname you’ll be happy with in the long run. To change your BattleTag after it’s been selected, log in to Battle.net Account Management, go to the Summary page, and click Change in the BattleTag section.
To add a BattleTag friend: 1.Open your Friends List (or the Social window) and click Add Friend. In Diablo III, you can also send BattleTag friend requests by right-clicking a player’s BattleTag in the game interface. 2.Type their full BattleTag and code into the appropriate field. 3.Click Send Request. 4.If the other player accepts your request, your BattleTag will appear on each other's friend lists.
BattleTag In-Game Functionality
Your Real ID friendships will not change. You can establish Real ID friendships with people you know in real life, and all of the features and benefits of Real ID will remain available to you. Real ID friends will see both a friend’s BattleTag and real name in their in-game friends list, along with information about what their friend is playing. Diablo III and Hearthstone players are required to create a BattleTag before they can play the game. Players must also create a BattleTag to use a Diablo III or Hearthstone-related identity on the forums