What is a multi? (in General)

I read many thread on this topic, and I have not very well understood what they are.

Are they a group of several players that exchange their accounts and play at various times so that they use their full load of BA every day??

One person many accounts; or alternatively one account many people.

From the FAQ:

Questions and Answers:
Q: May I have more than one account?
A: No. This is the first thing you are told when you sign up, but for people with short memories and/or attention spans, I reproduce this rule here.

The community polices "multis" fairly diligently. IP sharing is the main evidence in such cases, but is not in an of itself proof of guilt. If you share an IP with other players, you should avoid transfers (particularly one-sided ones) to each other to avoid the appearance of evil.

As with other cases where you need an admin's attention, if you suspect someone of violating this rule, post to Public Record:

Post the name of the user and the names of the "multi" account(s). If possible include the user_id in case the multi makes a quick name-change. (search for the user then hover your mouse over the link to the user's homepage. Look for "user_id_from_search" in your browser's status bar.)
Present what evidence you have to support your accusation. Examples include:
Relevant portions of chat or chatmail transcripts where the person admits being a multi
Player-player transaction logs showing suspicions behavior
Store logs showing people with the same (or similar ip addresses)
Etc.
Present your information in a straight-forward and factual manner. Flaming and namecalling are unneeded and unwanted. (Particularly if you are wrong about the person being a multi).
(Thanks, Sukotto!)




Q: May I share my account with someone who doesn't have a CB account?
A: No. This was allowed in CB1 but it wasn't a good idea; it's disallowed in CB2.