from scrapper to scrapper as each person does a page or layout for it. You send it on to the next person when you have completed your layout, and wait for the person in front of you to send the next one. So each journal/album starts w/ one person, gets sent to everyone else in the group in order, then ends up back at the original owner...thus, the circle.
They are usually themes, decided by the group. Maybe "What I Value the most...", "Why you mean so much to me...", so it can be people who know each other well, or not.
HTH
Kris