What is stored in the database?

[spambaggs]

Hello.

I am considering using roundcube as a webmail front end for my IMAP server.  I can see that It requires a database, but I'm curious what ends up stored here.  
The reason for asking, is to understand if I need to be concerned with backing up the database.

Thanks

[rosali]

Users will loose their preferences, contacts and identities if the database gets corrupt.

Messages itself would be not affected.