Information about the Battle.net friend notification window popping up in the middle of the screen.

How to play select Battle.net games in offline mode

Offline save file save path information.

Information about how the Appear Offline setting in your friend's list affects visibility in Battle.net Games.

Troubleshooting for Hearthstone connection issues on mobile devices.

Troubleshooting for issues loading the BattleTag or Real ID friend list

Blizzard servers could not be reached or may be offline. 

Versus mode requires being logged in to Battle.net

Eggs that hatch while your character is offline will push their loot to your bags when they next log in.

What to do if one or more of your Diablo II: Resurrected characters are missing