Search Engines Index

Search engines index the web's link structure and page contents, they find two distinct kinds of information about a given site or page - attributes of the page/site itself and descriptive about that site/page from other pages. Since the web is such a commercial place, with so many parties interested in ranking well for particular searches, the engines have learned that they cannot always rely on websites to be honest about their importance.

The theory goes that if hundreds or thousands of other websites link to you, your site must be popular, and thus, have value. If those links come from very popular and important and trust able websites, their ability is reproduced to even greater degrees. Links from sites like USAToday.com, edu. Gov.in and many others carry with them underlying trust that search engines then use to promote your ranking position. If, on the other hand, the links that point to you are from low-quality, interconnected sites or automated garbage domains, search engines have systems in place to discount the value of those links.

The most well-known system for ranking sites based on associate data is the simple minded formula developed by Google's founders - Page Rank.

Page Rank, which trusts on log-based figuring’s, is described by Google in their Technology section:

Page Rank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page's value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at considerably more than the sheer volume of votes, or links a page receives; for example, it also analyzes the page that casts the vote. Votes cast by pages that are themselves "important" weigh more heavily and help to make other pages "important." Using these and other factors, Google provides its views on pages' relative importance.

Page Rank is gained by mixing all the links that point to a particular page, adding the value of the Page Rank those they pass (based on their own Page Rank)

Google's tool bar includes an icon that shows a Page Rank value from 0-10

Page Rank, in center, measures the brute link force of a site based on every other link that points to it without significant regard for quality, relevance or trust. Hence, in the modern epoch of SEO, the Page Rank measurement in Google's tool bar, directory or through sites that query the service is of limited value. Pages with PR8 can be found ranked 20-30 positions below pages with a PR3 or PR4. In addition, the tool bar numbers are updated only every 3-6 months by Google, making the values even less useful. Rather than focusing on Page Rank, it's important to think holistically about a link's worth.