Like many, I’ve spent the past few weeks playing around with the new social network Google+.  The most interesting aspect of Google+ is Circles, the tool for organizing contacts (social graph) on the network.  Here’s a quick video overview:

So why does Circles matter?  It differentiates Google+ from Twitter and Facebook.

On Facebook, to have a relationship with someone you both have to opt in.  You have to become “friends”.  Due to this restriction, most interactions on Facebook are private.

On Twitter, you follow people and people follow you.  While there are ways to figure out if someone reciprocates your follow, it isn’t critical to the use of the service.  The primary point of Twitter is to find interesting people to follow.  The service is primarily public.

With Circles, Google+ has sort of split the difference between Facebook (private) and Twitter (public).  They have left it to users to decide how they want to use the service.

When you decide to add a contact on Google+, you are automatically asked to put the contact in a circle.  By default, Google has a a few predefined circles.  Some of the predefined circles imply intimacy (Family, Friends), while others imply only loose connections (Following, Acquaintance).  You can also create custom circles.

When posting an update, you decide which of your circles to share information with.   And that’s it.

This is a really elegant solution for a number of reasons:

• Adding someone to a circle is less of a commitment than adding someone as a friend on Facebook. Circles just doesn’t have the drama associated with Facebook “friendships”.  At the same time, the inclusion by default of circles such as Family and Friends makes it possible for adding someone to to be more of a commitment than simply following someone on Twitter.
• Circles lets you define your relationship with someone in private. While you are notified when you are added to a circle by another user, you have no idea which particularly circle you are included in.  So someone that has added me to a circle called “BFF” will never know if I’ve only added them to a general circle called ‘Following”.  While this sort of grouping is possible to do in Facebook, it is not nearly as fundamental to the experience as it is with Google+.
• Circles forces you to categorize contacts. To add a contact, you have to put them into a circle.  You have to make a choice. This requirement forces you to think through how you want to categorize your contacts, which ultimately makes you think through how you want to use the service.

As a result of all of this, Circles allows people to use the service publicly, privately or through some hybrid model determined by the user.  Scoble can use the service to amass 40,000+ followers in a week while at the same time my college buddy can use it to post photos from his wedding only viewable to three people.

The sharing flexibility of Google+ allows the service to fill a nice little void between Twitter (public) and Facebook (private). If Google+ succeeds, I think it will largely be because of the elegance and flexibility of Circles.

What do you think?