Your guild will be asssigned a campaign for Cyrodiil. Think of a campaign as a server in otehr games. SO you will always be with the same 2000 people, you get to know your allies and enemies, and even enemy guilds. So what you accomplish (keeps you take) will remain the same (you will NOT be put in a different world where the same keep has different owners all of the sudden from different people fighting) but your campaign is always running , even when your not in Cyrodiil so when your not logged on anything can happen