Yes. This is a necessary consequence of Diablo 3's online cash auction system. All your stuff has to be stored on the server to prevent 'fraud'.

As you can see, the official system requirements include a broadband connection.

http://us.battle.net/support/en/article/diablo-iii-system-requirements

On further investigation, there appears to have been a rumour at some point that Diablo II will feature an "offline" mode, but this information is a year old, and Blizzard's system requirements seem to contradict it.

Q: Is there going to be an open/closed battle.net like on Diablo 2?

A: Very little is known right now on how Battle.net is going to work with Diablo III, mainly because they haven't done much work with it yet. It is unknown right now whether or not Diablo III will have an open/close Battle.net option. There will be an off-line mode but it is unknown whether or not you will be able to use those characters to play on-ine (sic).

(from http://forums.battle.net/thread.html?topicId=27800569797&sid=3000)

A more recent and presumably up to date FAQ on the Diablo III wiki appears to agree that there will be no offline play.

Yes. This is a necessary consequence of Diablo 3's online cash auction system. All your stuff has to be stored on the server to prevent 'fraud'.

As you can see, the official system requirements include a broadband connection.

http://us.battle.net/support/en/article/diablo-iii-system-requirements

On further investigation, there appears to have been a rumour at some point that Diablo III will feature an "offline" mode, but this information is a year old, and Blizzard's system requirements seem to contradict it.

Q: Is there going to be an open/closed battle.net like on Diablo 2?

A: Very little is known right now on how Battle.net is going to work with Diablo III, mainly because they haven't done much work with it yet. It is unknown right now whether or not Diablo III will have an open/close Battle.net option. There will be an off-line mode but it is unknown whether or not you will be able to use those characters to play on-ine (sic).

(from http://forums.battle.net/thread.html?topicId=27800569797&sid=3000)

A more recent and presumably up to date FAQ on the Diablo III wiki appears to agree that there will be no offline play.

Yes. This is a necessary consequence of Diablo 3's online cash auction system. All your stuff has to be stored on the server to prevent 'fraud'.

As you can see, the official system requirements include a broadband connection.

http://us.battle.net/support/en/article/diablo-iii-system-requirements

Yes. This is a necessary consequence of Diablo 3's online cash auction system. All your stuff has to be stored on the server to prevent 'fraud'.

As you can see, the official system requirements include a broadband connection.

http://us.battle.net/support/en/article/diablo-iii-system-requirements

On further investigation, there appears to have been a rumour at some point that Diablo II will feature an "offline" mode, but this information is a year old, and Blizzard's system requirements seem to contradict it.

Q: Is there going to be an open/closed battle.net like on Diablo 2?

A: Very little is known right now on how Battle.net is going to work with Diablo III, mainly because they haven't done much work with it yet. It is unknown right now whether or not Diablo III will have an open/close Battle.net option. There will be an off-line mode but it is unknown whether or not you will be able to use those characters to play on-ine (sic).

(from http://forums.battle.net/thread.html?topicId=27800569797&sid=3000)

A more recent and presumably up to date FAQ on the Diablo III wiki appears to agree that there will be no offline play.