How well do we know our friends?

I'm new to social networking. I completely missed the whole Myspace fad, and joined Facebook in November of 2010, shortly after new privacy changes sparked widespread controversy.  The Facebook I joined is more or less the same Facebook we have now, except for the the changes to the chat and message systems.  I can't imagine a Facebook where there is no news feed; the news feed is the heart of Facebook.  That is what truly allows us to know everything our friends post.
Within two days of creating my profile, I'd added close to 150 people; I was amazed I knew that many people.  It did help that my finally creating a profile was major social news.  At the time, I personally knew and interacted with each of these people frequently.  As time progressed, I began adding people I was familiar with but did not personally know.  After I joined the Clemson Class of 2015 Facebook Group I began adding people that I interacted with on the group page.  At that point, my friends list began increasing exponentially as my personal connections to these people began decreasing exponentially.
However, the title of this article, I'm So Totally, Digitally Close to You holds special meaning to me because Facebook is my primary method of communication with several friends.  Facebook has allowed me to "meet" members of the Clemson Class of 2015.  Through our group, which has over 2,000 members, we've found roommates, had questions answered about orientation, move in, and Clemson Connect stuff.  Now, we're using it to make connections and seek homework help.  Facebook allows me to keep up with what my friends are doing, even those who live hours away.  Over the summer, I was able to reconnect with 2 childhood friends I hadn't talked to in 10 years.  I have several friends that live many hours away; I have almost exclusively digital relationships with these people and have Facebook to thank for that.
One year ago I didn't have Facebook.  Nearly a year later, I've reached the point where I'm constantly checking it, making sure I keep my notifications clear and my messages read, reading nearly everything which comes into my news feed.  Facebook is a social networking tool; it's up to the user to decide how to use it.  It's experienced massive growth and essentially led to the death of Myspace.  Facebook has changed from a small social circle of close friends to a large tangled web of people all over the world, allowing users to utilize it to the full potential, finding people from all over, or simply "friend" those that are present in their lives.
While our friends lists are rapidly growing, and our intimate knowledge of these people is decreasing, we are using Facebook for its intended purpose: true social networking, becoming aware of and familiar with people who will be useful in our lives for some reason or another.