Google Page Rank

PageRank is an algorithm patented by Google that measures a particular page’s importance relative to
other pages included in the search engine’s index. It was invented in the late 1990s by Larry Page and
Sergey Brin. PageRank implements the concept of link equity as a ranking factor. PageRank considers a link to a page as a vote, indicating importance.

PageRank approximates the likelihood that a user, randomly clicking links throughout the Internet, will
arrive at that particular page. A page that is arrived at more often is likely more important — and has a
higher PageRank. Each page linking to another page increases the PageRank of that other page. Pages
with higher PageRank typically increase the PageRank of the other page more on that basis. You can
read a few details about the PageRank algorithm at http://en.wikipedia.org/wiki/PageRank.
To view a site’s PageRank, install the Google toolbar (http://toolbar.google.com/) and enable
the PageRank feature, or install the SearchStatus plugin for Firefox (http://www.quirk.biz/
searchstatus/). One thing to note, however, is that the PageRank indicated by Google is a cached
value, and is usually out of date.

PageRank values are published only a few times per year, and sometimes using outdated
information. Therefore, PageRank is not a terribly accurate metric. Google
itself is likely using a more current value for rankings.

PageRank is just one factor in the collective algorithm Google uses when building search results pages
(SERPs). It is still possible that a page with a lower PageRank ranks above one with a higher PageRank
for a particular query. PageRank is also relevance agnostic, in that it measures overall popularity using
links, and not the subject shrouding them. Google currently also investigates the relevance of links when
calculating search rankings, therefore PageRank should not be the sole focus of a search engine marketer.
Building relevant links will naturally contribute to a higher PageRank. Furthermore, building too many
irrelevant links solely for the purpose of increasing PageRank may actually hurt the ranking of a site,
because Google attempts to detect and devalue irrelevant links that are presumably used to manipulate it.
PageRank is also widely regarded by users as a trust-building factor, because users will tend to perceive
sites with a high value as more reputable or authoritative. Indeed, this is what PageRank is designed to
indicate. This perception is encouraged by the fact that Google penalizes spam or irrelevant sites (or
individual pages) by reducing or zeroing their PageRank.