"In 1967, Stanley Milgram, a Harvard social psychologist, discovered that Americans lived in a "small world" with only six or fewer connections between one another. Later, the Oracle of Bacon, a game named after a prolific Hollywood actor, Kevin Bacon, proved that our society was indeed characterized by six degrees of separation. In 2011, scientists at Facebook and the University of Milan revealed that our world had become even smaller in that the average number of links from one person to another was only 4.74 worldwide. So how are people connected and why do they create, maintain, modify, and dissolve their communication ties with others in the social network? This book provides an in-depth answer from a multi-theoretical and multi-level perspective. Being the first book to theorize social network analysis in the field of communication, this book has had a profound impact on my research. I would not have had completed my dissertation and earned my tenure without this book. I would highly recommend this book to anyone who is interested in understanding how humans are inter-connected and how communication networks emerge and evolve. As one of the readers commented on Amazon, "this reader called in sick to work in order to finish the book. If you are going to own one book about networking, it should be this book. Seriously."