Within real-world networks, nodes are unlikely to be dispersed evenly. They tend to cluster or form local groupings that are more tightly knit than the network at large. When two clusters are connected by a solitary link, but are otherwise unconnected and isolated from each other, that link is called a bridge.

Clustering can be witnessed in online personal utility networks like Slack or Facebook Messenger, where people form subgroupings that are more active than the broader network. You can probably see examples if you consider your own private use of those services. A similar clustering phenomenon also can be seen publicly on Twitter and YouTube among popular members of those networks.

The networks with higher degrees of clustering, measured by a "clustering coefficient", can have the very powerful network effects as described by Reed's Law (more on this below), which posits exponential increases in value as a network grows. A network with a high clustering coefficient will increase exponentially in value while it grows, while a network with low clustering will increase in value at a slower rate. There are tactics for increasing the clustering coefficient in your network, although not all networks are equally susceptible to forming clusters.