Classroom 2.0 is a site where you can share whatever you find interesting on the web with people who value your opinion (whether you know who they are or not), and where you can also find what's interesting from people whose opinion are important to you - whether they know who you are or not.
Everything on Classroom 2.0 is submitted by Classroom 2.0 users, and after they submit a story, website, etc. other people will read it and give it a thumb up or down. If that story receives enough positive votes, it is promoted to the front page. But...!
While there are other sites offering similar services, in Classroom 2.0 each user has their own "front page", and the stories promoted to a user's front page are determined only by the votes of the people this user has previously selected - these are what we call, the user's sources.
Say there's a guy named Joe Whittman. Say I like how this guy thinks and I notice he has a Classroom 2.0 account. I would add him as one of my sources right away! I want his opinion count when my "front page" is being shaped up.
But hey, perhaps Joe doesn't even know who I am. Or perhaps he knows me but doesn't care what I think. Should he be forced to add me as one of his "friends" simply because I trust his opinion?
