Webwhompers

A hub is a node in a graph with much higher degree than average. For example, nodes 1 and 2 are both hubs in the figure below:

Centrality is the mathematical term most commonly used to describe hubs. Degree and indegree are two common simple measures of centrality.

Google made centrality-based Web search famous, and centrality-based search engines now dominate the Web. If cluster-based search engines reveal something like a Web "table of contents," then centrality-based search engines provide quick shortcuts to "the good parts"--the most popular pages and pictures.

The sociological force behind Web hubs is cumulative advantage, or "rich get richer." Here is one important way that cumulative advantage impacts the Web:

1. When a Web builder is looking for online resources, he probably uses a centrality-based search engine like Google, and he is more likely to look at higher-ranked pages.
2. Pages atop centrality-based rankings are there because they are already popular (essentially because they have high indegree.)
3. Therefore Web builders are more likely to link to (and increase the indegree of) pages that are already popular. It is possible that Web builders will never even see the "good" pages that are not popular.
4. Therefore Google and its ilk, to some extent, drive a feedback loop that amplifies the popularity of whatever is already popular. In other words, the rank of a Web page next week has less to do with its content and more to do with its rank this week. The main change to be expected in next week's rankings is that disparities between high rankings and low rankings will increase. The rich get richer.