This chapter describes ten principles of social networks that affect buzz. The ten principles are:

1. The networks are invisible.
2. People link with others similar to them.
3. People live in clusters.
4. Buzz spreads through common nodes.
5. Information gets trapped in clusters.
6. Network Hubs create "shortcuts".
7. We talk to those around us.
8. Weak ties are surprisingly strong.
9. The Net nurtures weak ties.
10. Networks go across markets.

Let me focus here on principle #5 (Information gets trapped in clusters) which addresses a common misconception about buzz. You often hear about a product that "spreads like wildfire," but in reality this happens only in rare cases. One reason for that is that people live in clusters. Buzz can spread effectively within one cluster but is slow to leap outside these networks as illustrated in the following story.

I once promised a new customer of EndNote that I would help her install the software on her computer. On the designated day I arrived at her office. We had hundreds of users already at the university where she worked, so I was a little surprised when she asked me if anyone else around there was using EndNote. She was equally surprised to hear that hundreds of people in the same university were already using the software. The mystery was resolved after we talked further. She was a surgeon involved mostly in clinical work, rather than in basic research. Most of the users of EndNote at that university at the time were Ph.D.'s who did only basic research. There was a significant gap between them. Ronald Burt of the University of Chicago defines this type of a gap as a "structural hole"—"a separation between nonredundant contacts." It is important to realize that oftentimes different information circulates on either side of a structural hole. The surgeon certainly knew of the Ph.D.'s at her facility, and may have occasionally interacted with them. But most of her daily contacts were with other surgeons. They weren't talking about EndNote.

Also in this chapter: • The Busy Network Paradox