PageRank, the score of popularity for Google

The name PageRank, which is a trademark from Google, is a pun between Page Rank, rank of a page, and Larry Page, one of the two founders of the company, which owes his initial success with the implementation of an algorithm with the same name. This one classifies Web pages according to their popularity on the Web, therefore according to the number of link toward them.

The role of PageRank

PageRank intervenes in a second time: at the time of a search, the pages are selected according to keywords they contain. Then the pages which contain the same keywords are classified according to a whole of criteria among which PageRank.
Thus it is possible to reach the top of the results with a null PR, as soon as one is alone to evoke certain keywords.
On the other hand on competing searches, PR is very important.

The PR has also a role in the way a site is crawled:

"The number of pages that we crawl is roughly proportional to your PageRank." Matt Cutts.

Backlinks and outgoing links

The algorithm of PageRank takes into account entering links, the backlinks, and the links of the site towards other pages.
That does not prove only the links that one makes on other sites improves PageRank, because the initial algorithm is not used any more for a long time (according to Google). On the other hand it is confirmed by the sites of search engines that outgoing links, if they are relevant and if they point on sites of references, contribute to select a page at the time of a search.

The sandbox effect

One generally agrees to consider that the sandbox effect is noted at Google and not on other search engines.
The sandbox is a supposed temporary storage section or Google would place the new sites while waiting to assign PageRank to them.
One speaks also about sandbox effect when a site loses its classification in search results, and without for being removed from the index much, becomes unreachable because placed at end of the list (that does not affect it when it is alone to contain searched keywords).
It would be a sanction inflicted by Google to sites which arbitrarily create backlinks in quantity by the use of satellite sites and other artifices, as one will see it further.
Certain recent businesses (the BMW affair for example that was sandboxed for some days) made official the existence of the sandbox effect. ll would exist since March 2004.

The sandbox effect is denoted also in the fact that new pages take longer to be indexed by Google than by other search engines. There are divergent opinions, some estimating that the algorithm of Google integrates the pages more slowly, others that it is a measurement deliberated to fight spamming coming from satellite pages created to add backlinks.

Simplified sight of the PageRank algorithm

It is about the initial algorithm described by Larry Page and Sergey Brin and which is at the origin of Google.
Better PageRank will be obtained by a page with a greater number of links pointing on it but according also to PageRank these pages themselves have. If a page points on several others, the value which it brings is divided by the number of links. But the value which is acquired by links of quality being integrated into the page, it will be transmitted to the pages on which point this page.
That works even with internal link inside the site.

Artifices prohibited to try to improve PageRank

These artifices are generally detected by Google, which besides request that one denounces sites using such, which professionals gladly do when their competitors have recourse to them. These sites can be placed on a blacklist and removed from the index.

Cloaking
One put in the page links invisible to Net surfers, for example with a white color on a white background, but that the robots of search engines take into account since they are unaware of the attributes of presentations like colors.
Spamming
Consist in creating non visible pages to Net surfer containing quantities of links towards a site which one wants to promote.
Spoofing
It is the use of the "refresh" meta-tag. The page taken into account by the robots is another page of higher PR, and not that which is seen by the reader.

Techniques recommended to increase PageRank

There are however honest techniques to increase the PR of a site! One calls that search engine optimization, or SEO. (That goes beyond PageRank.)

Have a well defined subject for each page. It will contain a maximum of different keywords concerning this subject, with all possible synonyms. Obviously these words are integrated in sentences because the text addresses above all human readers.
Do not add too much outgoing links. Add only very relevant links on pages useful for visitors. But do not omit such links, they are part of the quality of a Web page.
Put links between the pages of the same site.
To obtain backlinks: create original contents, with an attracting presentation. Prepare and promote it as described in the SEO tutorial, to let it known.
Do not omit the <title> tag, the <h1>, <h2> and other sub-titles. All titles must be appealing, it is necessary that one wants to choose your link in the pages of results of search engines (that is taken into account for later position in the results).
The text of anchors is important for the score of a page. It must contain significant words and in connection with the contents of the paragraph.

More information

How Google determines the score of a page. All criteria taken into account according to a patent deposited in April 2007 by Google.
How Google tweaks its search engine. Article from the New-York Time.
Google PageRank, what do we really know about it? List of rules and summary or articles and tools about PR. Not all is true in the article, for exemple: "Adding new pages can decrease Page Rank" is false.
Analysis of PageRank.