Learn Flag with NodeOne
Flag is a module used for marking nodes, comments or users with 1/0 marks – for example for flagging spam comments, selecting content to promote to a sidebar, or marking other users as friends.
Flags can either be set global – everybody share the same flagging – or on a per user basis – where each user gets to set their own flags. With the Session API module, you can allow anonymous users to set their own flags as well!
What makes Flag useful is primarily its integration with the Views and Rules modules.